With the verb δέχομαι, the aorist indicative middle, 1st person singular is given by Pharr as ἐδέγμην. I'm not great with athematic aorists, and I'm not sure about the consonantal rules. Is the following anywhere close to correct?
Singular 1st ἐδέγ-μην -> ἔδέγμην
2nd ἔδεγ-(σ)ο -> ἔδεγο, ἔδεξο ;γ in ἔδεγσο becomes κ by partial assimilation to σ, then κσ becomes ξ.
3rd ἔδεγ-το -> ἔδέκτο ;γ becomes κ by partial assimilation to τ.
Dual 2nd ἔδεγ-σθον -> ἔδεχθον ;σ between two consonants dissapears. Then γ becomes χ by partial assimilation to θ.
3rd ἐδέγ-σθην -> ἐδέχθην ;σ between two consonants dissapears. Then γ becomes χ by partial assimilation to θ.
Plural 1st ἐδέγ-με(σ)θα -> ἐδέγμε(σ)θα
2nd ἔδεγ-σθε -> ἔδεχθε ;σ between two consonants dissapears. Then γ becomes χ by partial assimilation to θ.
3rd ἐδέγ-ντο -> ἐδέγατο ;"vocalic" ν becomes α.