Frame wear from swingarm

Hey guys - has anyone ever seen this before? It looks like the swingarm has worn grooves in my 1976 250 WR frame. From looking at the parts manual it appears I have all the parts/bushings. Is something missing, was it overtightened, swingarm bushings worn out? Something else?
Thanks,
Mark

I don't know about '76 but all of my early to mid 80's bikes, I have six of them, had a stainless steel thrust washer between the swing arm and frame. My first Husky ('80 CR390) got the same wear marks, bearings and swingarm housing, wore the washers completely out! That was my first lesson on preventative maintenance (They were expensive). I just replaced them and I haven't had problem since. Proper adjustment is the key, I think.

At least the holes are not egg shaped. I have 3 frames to correct that issue on

There were no washers at all (unless you are talking about what looks like washers on the engine clamp plate) and the damage wsa already done when I bought the bike. If these are the wahers that are supposed to be there, it could have been overtightened at one time. Are the thrust washers integral to the clamp plate?

Yep - I see them now in your photos. I was going by the parts manual that doesn't show any washer there that I can tell (which I believe you alluded to in your post). After reading your post I pulled out my shop manual and it's shown in fig 6-1 on page S E-6. Do you have the dimensions handy?

Thanks for the great advice, as usual!!!

Thanks to everyone that posted advice and info!!!