[_paralyzed_]

a little lube never hurts.

The only thing I can imagine is that you have some binding somewhere in the drivetrain. This can sometimes be tricky to pin point, as sometimes bearings only fail under load, but feel smooth free wheeling.

Are you running big heavy aftermarket tires? They really stress drivetrains. Have you added a lot of weight by adding aluminum hopups?

Are you landing jumps while still on the throttle?

You said the 2nd gear lasted a month, did the first one last a lot longer? That would indicate a new problem.

Failing all that, is your slipper too tight? Maybe loosen it a little.