I have a couple suggestions if you are short of money. First checking the size of the shim is easy. Take out the gib and clean it and run a wire into the gap the gib was in and wrap the wire around a rag and pull it trough there with some solvent on it to clean out the hole if it is dirty. Then whit is clean stone or smooth cut file the ends of the gibs and slide the gib in so the slot that the gib screw fits in and with the bigger round flange is about 1/2 way into the. Then take a feeler gage and check what the opening is.
Depending on how much the gap is, you could shim the back side of epoxy on some Rulon 142 to the gib or on the back side of the saddle. Rulon is self lubricating plus it compresses a little, so it will compress on the tight ends and turn easier Your table is bent too, convex probably .005 to .010". The convex of the table can also make the ends get tight plus wear. I have some orders I need to get out. I'll come back later. Rich