Try wiggling the shifter up and down agressively while someone rocks the machine back and forth. The shift drum is probably stuck between positions. If this works just keep riding it. It's just a common banshee flaw. If this doesn't help you can get to the shift mechanism by removing the clutch side engine cover.

 

I went riding today, and after...dont know...like 3-4 hours of riding, I couldn't get more than one gear down. I thought first it was because of the crappy shifter, but when I stopped, it looked like if the spring (is it exists) that gets the shifter back into place is off.
When I push down on the shifter, it doesn't come back up...i can lift it back into place though.
Did this already happen to anyone of you? What was it. I'm gonna open the engine by the right side case...I hope I will be able to see in the gearbox...don't tell me I have to take the engine out of the frame and open the gearbox from the middle.

Any help appreciated.

 

Dunno about shee's but on my banana the shifter spring is on the right side of the tranny(sitting on quad). The shaft goes thru the whole tranny and the spring is located behind the clutch basket.

PS: Achete un Clymer !!!