'93 Spirit Transaxle Problem

This one has me puzzled, While cold, it will go into any gear just fine, once it warms up it loses forward gears. Reverse will still work though. Shut it off for just a few seconds, prestow you have forward gears again.. just not for long. Anyone have an idea as to mechanical prob or electronic?

Cheers

which transaxle do you have the 3 or 4 spd.