HOW CAN THESE LISTS HELP YOU?

A good deal of the verb forms you will encounter will not be “canonical” (this is, for memory's sake, not a durative 1 or 3, an aorist II or IV, a future 1 or 2,  or a perfect I); even if the form is canonical, it may come from a durative (which is also the lexical source form) that is itself non-canonical. In those cases it will be hard (even impossible) to find the correct lexical source form and the sense of the verb.

Examples:

1) λαβόντες: it is not difficult (I hope) to determine this as an A ptc >M N pl; the lexical source form, if this were a durative, should be *λαβω, but such a word is not included in your lexicon. In that case you must isolate the stem from the form and look this up in the list; in this form the stem is of course λαβ- and having selected the stems with an initial λ- you will find there a stem λαβ- from a lexical source form λαμβάνω which has an aor 1 ἔλαβον of which this is a ptc form. So λαβόντες is aor A ptc >M N pl and means “having grasped/taken”. [Conoisseurs would have noticed the accent on the –o- of λαβόντες and have realised that the form was an aorist]

It is however not always so easy as this: as often as not the form encountered in the text is from a composite verb (e.g. συλλαβόντες) and finding the correct stem necessitates one more step: the realisation that this is a composite and snipping off the preverb.

2) δείξατε: this will be determined (tentatively) as an aor (type II) A imp 2^nd pl, but the expected durative (δείκω, δείχω, δείγω or δείττω) will not be found in any lexicon; therefore recourse will be had to the list of stems and there one will find the stem δεικ- from a durative δείκνυμι. Of course, while you are searching the lexicon for δείκω etc., your eye may meet δείκνυμι, and recourse to the list of stems may be passed over; but you must not forget to ascertain that δείκνυμι indeed has an aor ἔδειξα.

N.B. A special difficulty will have to be met in the case of composites with preverbs that end in a vowel that is also the first letter of the simple verb:  is ἀπολέσαιτε to be divided into ἀπο- & -λέσαιτε, or ἀπ- & -ολέσαιτε? Failing routine and feeling, both will have to be tried.

The above examples have been chosen on purpose for their being completely straightforward, but as usual elsewhere, life here is not always nicely simple. To give but one example: ἐπήλασαν looks simple enough: an aor (type II) A ind 3^rd pl, but what is the stem? As an aor ind it must be an augmented form. Is the initial ἐ- the augment of a stem πηλα-/πηλαΤ-(T means any dental, i.e. δ,θ,τ), which would produce a durative πηλάω/πηλάζω etc? The answer to that is negative, as the lexicon contains no such word. This means that we must try a configuration with the preverb ἐπ-, so that the -ή- is an augmented –α- or –ε-, or even –η-; of these, only ἐλα- (see lists) exists, with a durative ἐλαύνω. Only after all these complex mental and page-turning acrobatics ἐπήλασαν reveals itself as aor A ind 3^rd pl of ἐπελαύνω.

When you are bothering yourself about composite forms, you must not forget that the preverbial element is subject to changes: ἐνέλιπεν (aor A ind 3^rd sg) is to be found lexically under ἐλλείπω. Such changes are treated under “composites”.

Sometimes (mainly in the perfect) active forms hava a sense that is more medial or passive than active, e.g. ἔαγα of ἄγνυμι means “I am broken” and not “I have broken”. The other way round, medial futures have active sense, e.g. ἀκούσομαι of ἀκούω means simply “I shall hear”. In the list a  ^A or ^M will be added to mark such phenomena: ἔαγα^M,  ἀκούσομαι^A . Of course  these matters are also taken care of in the lexica.  

 Some conventions for reading the lists:

In the first column, arranged alphabetically, you will find the stems on which uncanonical forms are made; sometimes, to make assurance doubly sure, forms have been added that strictly should not be there (e.g. ἐγηγερ-, which is  an Attic-reduplicated form of ἐγερ-).

In the second column one finds the durative(s) with which the forms on this stem must be associated; sometimes the durative is very unexpected, for example the dur φέρω for forms on the stem ἐγκ-. When the durative is not strictly formed on the given stem, the sign < is added preceding the dur.

Future Passive forms (in any case not very frequent) are not separately given, as they may easily be derived from the P aor:  replace –ην by –ησομαι.  
To avoid monstrously big files, I have made a separate file for each letter of the alphabet, so that when you have isolated the stem, you must find the forms made on it by selecting the initial letter above or below, then scrolling to the stem you want.

For the curious here is some theory about stems in Greek :

 English, being a language that has jettisoned almost all flection, does not have much to compare, but in (for example) “drive, drove, driven” there are three variations of one stem in the total conjugation of that verb, and there is also a number of other words derived from that stem: “drift”, “(a) drove”.

In the Greek non-canonical verbs there is lot of this kind of variation about, and if one surveys the whole set of words derived from a stem, one can observe a surprising number of different variations. In the durative γίγνομαι the most simple variant ( γν) is found of a stem that shows a lot more shapes: ao ἐγενόμην, pf γέγονα, fu γενήσομαι, pf γεγένημαι, sbs γένος, adj γνήσιος, sbs γενέτωρ. These are only a few of the many derivatives, chosen to show all existing shapes of this stem. From this and similar cases linguists have distilled a system of stem variation (C means consonant, V means vowel):

                           C₁ +Vzero/e/o+C₂ +Vzero/ĕ/ē  [the first zero-variant often has an –α-]

This makes nine possibilities per stem of this kind. Sometimes there is even length-variation in the first syllable (ο/ω, ε/η).

Not every possibility of every given stem is actually found, although γν c.s. do their best.

Other examples: (πνθ->) παθ, πενθ-, πενθη-, πονθ-, παθε-, παθη- (ao ἔπαθον, sbs πένθος, sbs πενθητήρ, pf πέπονθα, vb εὐπαθέω, ao ηὐπάθησα); βαλ-, βελ-, βολ-, βολε-, βολη-, βλη- (ao ἔβαλον, sbs βέλος, sbs σύμβολον, vb δισκοβολέω, pf ptc βεβολημένος, pf βέβληκα).

The (C₁+ o+C₂+zero)-variant has a tendency to appear in A pf II & III, the (C₁+ zero+C₂+zero) likes MP pf and P ao V: A pf τέτροφα, P ao ἐτράπην, MP pf τέτραμμαι of the verb τρέπω. Naturally the stem τραπ would appear in quite another place of the lexicon than τρεπ so all this causes considerable difficulty when one is hunting up the lexical form; therefore all these variant stems are included in the alphabetical list of verb stems that concludes this short grammar: if you encounter problems (that are not due to muddled thinking), isolate the stem from the form and look it up in the list; there you will find all formations that are made on that stem. Let us take for example the form ἐπετεταλτο: this would appear to be an (athematic) ΜdΡ pf ptc formed around the stem (ἐπι)ταλ; but the lexicon contains no verb of that kind, so now you simply click on HOME then LIST OF STEMS (or STEM, followed by the initial letter of the stem you wish to seek out) and look up ταλ, which turns out to be a variant of the verb τέλλω, and there this MdP pf is listed.

Another frequent type of stem variation is the --/+ σ-: γνω-/γνωσ-, ἀκου-/ἀκουσ-.

*Τιμάω has stem τιμα- in the durative, but τιμη- in the other phases; this goes for all verbs in -άω, excepting when –α- is preceded by –ι-, -ε- or -ρ-: then the stem remains the same as in du.

*Φιλέω has stem φιλε- in the durative, but φιλη- in the other phases; this goes for all verbs in –εω, excepting a few which cause no difficulty.

*Δουλόω has stem δουλο- in the durative, but  δουλω- in the other phases; this goes for all verbs in –οω.

These three types of variations are considered to be regular and are not included in the list of stems.