Here's a short description of one kind of semi-irregular verb in Arghish.

Postbases

Some verb lexemes have single-phoneme postbases which are suffixed to the root in the bare form, but which are preceded by certain suffixes in the conjugated form of the verb. These are probably fossilized aspectual suffixes in origin. There are four postbases: the most common postbases are <-z> and <-g>; the postbases <-d/-r> and <-y/-i> are less common.

The postbase follows suffixes like the reflexive <-iši> and is inflected directly to the preceding affix.

Bare form: (<root) "gloss" / Inflected form with <-iši> 'REFL':
gahz (gan-) "cut" / ganišiz
zolg (zol-) "pick up" / zulišig
kaghd (kagh-) "lead" / kawišir
bay (bah-) "touch" / bayši

After the suffixes <-an> (plural subject) and <-um> (past tense), the nasal of the preceding suffix disappears.

Bare form: / Form with <-um>: / Form with <-an>:
gahz / ganuz / ganaz
zolg / zulug / zulag
kaghd / kaghur / kaghar
bay / bawi / bahay

Other suffixes can follow the postbase, such as the singular imperative <-a> and the reciprocal <-ahg>.

Bare form: / Form with <-a>: / Form with <-um> and <-ahg>:
gahz / gazza / ganuzahg
zolg / zolga / zulugahg
kahgd / kaghra / kaghurahg
bay / baya / bawyahg

Some verb lexemes appear to have a postbase in inflected forms, but not in the bare form or in forms where the postbase slot is adjacent to the root.

Bare form "gloss": / With <-a>: / With <-um> and <-ahg>:
ughd "remember" / ughda / ughduzahg
laš "dig" / laša / lašuyahg
khrez "be old" / khreza / khrezugahg

At least one verb appears to have one postbase in the bare form, but another in the inflected forms.

Bare form (Root) "gloss": / With <-um>: / With <-um> and <-ahg>:
mord (mor-) "listen" / muruz / muruzahg

And some verbs, as indicated by comparative evidence with other Arghic languages, have a postbase which has been reanalyzed as part of the root:

Bare form "gloss" / With <-um> / Proto-Arghic etymon:
grar "recite poetry" / grarum / *[something without the -r]
barg "strangle" / bargum / *[something without the -g]


Maybe in the next post I'll give an explanation for how a verb for "to be old" can have a reciprocal form...