Holy Moses Delta Red, when I seen your pictures it looked like right out of the book Johnny Tractor and his Friends with Farmer Fowler.
The rattle chain may be catching on some tin or something and noone has mentioned this yet. We found out the hard way after putting THREE aprons in our 105 starting in 2010. Last year the whole dam chain balled up, bent the shaft. Our slip clutch on the raddle chain was welded at one time, that didn't hold so my brother drilled 2 holes through the slip clutch jaws and put 1/4" grade 8's through only to destroy that, before finding out that the whole platform the chain rides on and carries the grain was disintegrated. So last fall we pulled the whole ball of wax out and had a machine shop build a solid platform which we slid in from the front. It was not an easy job and took my brother and I about 60 hours from start to finish. New sprockets, new bearings and one new shaft, and a new sidehill chain.
Our 95 is looking pretty thin as well, especially up near the drive sprockets, it was starting to crack so it got JB welded last weak. If I were you, I'd check that tin platform your apron rides on and see if a slat is catching somewhere. We pulled the sieves and I crawled up in there and it was way worse than what I could see looking in from the sides. After seeing what we have been through, I can just about guarantee everyone else will have the same set of problems considering their age.