I have 2008 KLR 650. 32,000miles.
Have been touring with loaded bike, and rode 1-2000km with chain too tight. During the first 1000km, my oil went below minimum mark for several hundred kms (I wasnt aware they burnt so much oil).

Slowly developing after this, I have noticed the following problems:

Shifting from neutral to first, and first to second, results in a decent clunk, and/or a bit of gear grinding. This can sometimes be reduced by holding in clutch for 10secs, chirping throttle etc.

The rear hub has about 5mm of play, in the direction of drive. It also has back and forth play (hold top and bottom of rear driven sprocket, wiggle away and towards = play).

Ive changed oil, clutch cable (plus lube). No change.

Have removed rear sprocket, inspected rear hub, cush rubber looks decent. Bearings operate well. When replacing rear sprocket/hubb assembly, it doesnt seat all the way in. It sits 0.5-1mm proud. So the circumference of the hubb does not seat/marry, resulting in 0.5-1mm gap, hence the back and forwards play. Only the inner spacer marrys with the bearing either side. When axle is tightened, same situation. When I remove the spacer inside the hubb, it seats perfectly.

Thoughts:
Low oil levels have warped damaged clutch plates.
Tight chain has slightly bent drive shaft, somehow resulting in gear grind.
Tight chain has pulled on rear sprocket, slightly bent something, and skewed it out (allowing bearings to move...)...
Left side rear bearings (wheel and hub) have moved towards eachother slightly, hence the spacer creates just too big a gap.

PS: Theres enough drive chain lube oil around the front sprocket, so I havent checked for oil leakage about front sprocket yet.

Does anyone have any thoughts? Thanks very much for any input in advance.