In the process of fitting a new chain and sprockets, I inspected the swing-arm bearings and linkage to find that 4 of the 5 bearings in the shock relay arm were gone or going. I changed all 5 bearings and should be good to go. Oil seals #25, bearing #26, both # 10's and both # 20's.
(http://fjowners.com/gallery/9/150_10_04_16_8_40_55.gif)