Can you re tap them to the next size up? I worked on and around industrial machinery for years in a production environment and found out that just about ANYTHING can be fixed if you put your mind to it. I just made/machined an AR15 buffer retainer for a guy the day before a shoot. Took a piece of round stock, a drill and a file. I think the one I made on my front porch was better than the original. They make threaded inserts that will repair your threads.