Duck926 replied to motorberus's topic in CRF250L/M/RallyHas your dad owned it since new? Even then, I've forgotten things I've done just a year ago - did you check the sprockets to make sure?
I think that if the plates are "scrubbed in" and the oil is clean, then the plates aren't disengaging enough. Try to get more travel on the lever with the cable adjusters. If you can't get enough then, you may have too thick of a stack, ie. an extra plate or out of spec plates, and then you'll have to go inside the case again and verify the stack height.