On my wife's Tourer, it looked like the same thing happened to the previous owner. His solution was to drill out the remaining threads and install 1/4-in bolts and nuts. I didn't like the idea of having to deal with bolts and nuts and carry a different side wrench on trips, so I machined some stainless steel inserts and pressed them in from the back side (with a coating of the permanent type locktight). This let me go back to the stock mounting hardware.
-RP
