Technical Third gear pops out

[Nereidi]

My third gear has been popping out. It will stay in gear if I hold the stick forward. It only happens in third gear. Any way to fix it short of dropping entire transmission?

 

[bugsymike]

My third gear has been popping out. It will stay in gear if I hold the stick forward. It only happens in third gear. Any way to fix it short of dropping entire transmission?

Sadly it sounds like a gearbox rebuild.