RM125 RM125 Brown gunk buildup in clutch housing

I have just acquired a RM125 1995 and the clutch was needing some attention.
I have removed the cover and found a buildup of brown gunk in the whole area.
Anyone have a solution? that is painless ( not rebuilding)
 
It’s dry, almost rust looking. It is tough to wipe off, needs something more.
Also found a build up of sludge in bottom.
Sounds like a bigger project than I expected.
Thanks
 
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