Sounds like you probably need new keys and springs, classic symptom of popping out of gear when you let off is bad keys. That’s the problem with shops that don’t know these transmissions specifically. 4 speed transmissions all basically work the same way, the thing with A833’s is there were different variations of the transmissions over the years, mix and matching parts causes nightmares with this kind of stuff. I have got transmissions in with 2 different style hubs in them, one early style narrow key and one late style wide key. This and the wrong shift tabs/linkage are the 2 biggest problems I find when things don’t work correctly. If I can recommend anything, make sure you do your research, and or have someone that knows these transmissions do it for you.
