4KS auto cold=no shift (was 5KS auto)

[Andrei Kogan <abk@phy.duke.edu>]

works?  How hard are these
>>trannies to rebuild?  What has to be replaced to get it going correctly?
>
>The whole thing.
>The job itself is quite simple. The Bentley gives complete guidance. I did
>my 79 5KS 4 times and got VERY good at it. 
Dave,

Maybe I have a question for you then: the tranny in our 4000K was rebuild 2
years ago. The original problem was a stripped brass governor gear, and I
was cheap and didn't want to spend $400 on a new governor, and I couldn't
locate a used one. Anyway, they rebuilt the autobox later on, had a LOT of
trouble getting it back together --- it kept flooding the diff. Finally,
they ordered a whole new differential and it was OK for two years. Just
recently, it started acting funny again: When cold, the transmission won't
upshift. If I let the engine warm up for about 10 minutes, or just get
going and drive for maybe 1/4 of a mile or so in the first, it shifts and
since then works fine for the rest of the day. While malfunctioning, both
shift points (1-2 and 2-3) are late.

I had someone VERY tranny knowledgeable look at it. He replaced the
governor seal and some seals in the valve body and told me everything
inside looks normal. However, it didn't eliminate the problem, although the
warm-up time appears to be shorter. 

What would you suspect? 

Andrei