OK heres my bike.
Trek 6700 frame
Shifter Deore Mega 9
Rear derailer Shimano LX
I have been riding this bike for about 4 years. Recently I have been haveing major problmes with my chain droping from a low (large) gear to a higher (small) gear. This appears to be starting on the top of the casset and this is almost always occuring when im putting some torque on it. My derailer works perfectly shifting when theres little torque applied. My casset is the original and derailer the original. MY derailer has some play in one of the middle joints from a pin thats worn out its hole a little.
Im looking for some opinions on what the cause is, because this is driving me nuts. Also I dont have the $ to go replaing this and that searching for the problem (poor college student). I think my casset could be worn but wanted some other opinions. If i replace my casset should I replace my chain too?