Leaking oil seal
 

HI my xt600 recently dropped about 500ml of oil out of the gear selector shaft oil seal when i gave it a serious ride. does anyone know if this seal is replaceable with out completely disassembling the motor to take the gear selector shaft out? also the shaft has about 5mm movement in-out of the engine, is this wrong too?
ps i am really broke so i am looking for quick simple fixes

No problem
 

yes, it is replaceable easily. Pry the old one out, careful not to damage it's seat in the crankcase.
Buy a new one in a good car parts shop max 5 US$. Lubricate the sides lightly and push in place.

To slide the old one off and the new one one remove gearsshift pedal of course.

Movement gear selector shaft: this is normal.

Auke