3rd gear pop out

I have a 91 corolla 1.6. Third gear won't stay in place. The shifter pops back into neutral. Would it be better to replace the third gear? or what are some opinions on what this is or what to do or how to fix it. Or would it be best to just get a rebuilt or junkyard transmission?

I don't know exactly the cost comparison, that's really up to you to call around and ask after getting an informed opinion as to what the problem could be...broken shift fork? bad throw-out bearing? broken gear? Get estimates for fixing versus buying a used tranny and replacing.

If it were me, you would probably be slightly better off having yours repaired because no matter which way you go, the engine and tranny has to come out. With it out, they can replace the broken components, check and adjust the rest, install a new clutch plate and you'd get a good tranny with a decent warranty. Go used and you don't know what you'll get...sure they'll probably warranty it too and you'd get it back faster, but they likely won't crack the case and check it out before installing it. But you can ask for a newer lower-mileage tranny, albeit probably at a premium. Something like this you want done right the first time.

Good luck!