Had car at trans shop and rebuilt 5 speed manual driving popped out of gear on 2001 Chrysler PT Cruiser

Trans rebuilt and as been at trans shop going on 5 times seems to pop out of gear and will not go back in. shifter seem to be working fine could this problem be in transfer case or how cv joints couple to it. NEED HELP has any one had this problem before

Asked by for the 2001 Chrysler PT Cruiser
sounds like an internal a 2nd opinion then return with that info to orig repair shop