so what keeps it in gear then? also these are not straight cut, they are diagonal so the argument is not valid...unless the gear is damaged the only other item is the synchro? Why does my Transmission pops out of gear transmissions
"..Popping out of gear is a common problem when it comes to manual transmissions. The most common reason a manual transmission would jump out of gear is due to low or contaminated fluid, worn synchronizers inside the transmission, or improperly adjusted shift linkage..."
if you have more experience than i or the linked gentleman or the other transmission gurus i go to please enlighten us...also OP please let us know what yours is so we can all learn something new!
GEAR POP-OUT CAUSES AND FIXES-GBox Transmission
WC Engineering : 5th Gear Pop-Out
i guess the other bearings could cause clearance issues, either way the most common ones include them...but again your input on why this is happening will be lovely to hear! instead of just naysaying a post with no additional technical input/backup...