That should be fine, then.
The other question I'll ask is, how hard is it to move the shift lever? If it moves easily but doesn't return to center, it's probably a spring problem. If it's hard to move it could be the shift shaft seal is full of crap, or the shift shaft itself may be buggered in some way. Either way, pulling the mission cover just gets you into the selector mechanism, not the whole transmission. It's pretty straight-forward, really, once you get eyes on it.
cheers
mystic_1