I expect Paul made those sleeves because the frame bosses are allover the map, in tolerances.

and someone jammed the sleeve over the boss with the pressing force of the fixing bolt,
rather than dressing the boss with a file, so it didn't take so much force.

+1 on potentially mushrooming the frame boss .

But worst case , Burn paint, take the boss' off the frame
and install new ones , then do a repaint.