I have not seen shims on that assembly, what generally happens is the post where it screws into the upper assembly after years of closing bends the sheet metal. Check and see if it is straight. You want it to open and close without catching because if it hangs up you will be stuck. The latch assembly (lower) has some adjustment when you loosen the 4 attaching bolts. It sounds like it is not that far off. Good luck, test fit first to make sure it latches and unlatches at the first catch before you slam it.
