Wow its in pretty good shape for a 94. That was a simple atv. Just look under the front end, theres nothing to it. Simple and effective design.
Same thing goes for the engine. If your mechanically inclined you should be able to pull the motor and split it open.
BUT before all that have you drained the oil and looked for pieces of gear that may have broke off In the drain pan?
How does the shifter feel when you shift up?
Do some simple checking first before anything crazy and make sure of what's going on.
But this all depends on how handy you are.