For the verb τρέφω, to nurture, Pharr lists the principal parts for the Homeric dialect as τρέφω, θρέψω, ἔθρεψα/ἔτραφον, τέτροφα, τέθραμμαι, ἐτράφην. (Wiktionary also lists ἐθρέφθην as a possible aorist passive, but its absence from Pharr suggests to me that it didn't exist until after Homer.) I haven't specifically studied the aorist passive, so I'm looking up the following in a grammar that I found by googling and which seems to be for koine. (I can't find the relevant material in Pharr.) Because the aorist passive is ἐτράφην rather than something in -φθην, it seems like it must be a 2nd aorist. The 2nd aorist passive uses endings -ην, -ης, -η, -ημεν, -ητε, -ησαν, and therefore I would expect the 3rd person plural to be ἐτράφησαν, and indeed that's what Wiktionary lists.
But in Iliad 1.251, we have this:
... οἵ οἱ πρόσθεν ἅμα τράφεν ἠδ᾽ ἐγένοντο ἐν Πύλῳ ἠγαθέῃ, μετὰ δὲ τριτάτοισιν ἄνασσεν·
Project Perseus parses τράφεν as aorist third-person pl. passive. The augment is omitted, which is no big deal, but why is the ending -εν? I would expect that to be an active singular ending.
I'm guessing that this is something that changed between Homer and koine...?
Can anyone point me to a systematic, concise, and well organized presentation of how to form all the tenses in the Homeric dialect? I'm finding it very frustrating that the material in Pharr is scattered all over the place, and Pharr's index is very poor.