Non Volvo(toyota rav4) manual transmission question

[c70_lindsay]

My aunt has a Toyota rav4 with a manual transmission. It won't stay in 5th gear, it always "pops out". Generally speaking if a trans is doing this could it be a simple linkage that needs to be adjusted or a trans rebuild? Sorry for posting a non volvo query but I figured I'd ask here first (hey, I trust you guys) before signing up and searching a rav forum. Thanks!