JDGirl
I am just curious as to where the shear pin/bolt was located that you replaced,I couldnt see anything new on the photo's you posted. I also have an old Servis brand hog. If your's is similar to mine,and by the photo's it look's like it.Where the drive line coming from the tractor bolts to the cutter, those round plates are actually two seperate pieces. The driveline bolt's to the outer round plate,and the inner round plate bolt's to the gearbox.There should be a shear pin that bolts those two plates together.Without the shear pin ,both plates turn independant of each other and would exibit exactly the problem you are describing..That may have been the one you replaced,if not take a look.I blew your picture up as far as I could and I think I see a portion of the broken shear pin hanging out toward the gearbox..If we were just a little bit closer neighbors,I would take a look at it for you..
Regard's
Sean
PS
Your Brothers and Nephew's need need a lesson in courtesy..Just my opinion..so nobody come unglued