I think the size difference is just wear.

The fix for that is new nylon rollers and rivets from The Filling Station. Link
Drill out the rivet and replace with the roller and rivet and peen them in place. Pretty easy job. I used a cold chisel on the end in a cross pattern to expand the end of the rivet.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.