I don't have a lot of experience with shop mechanics. Though one time I did bring in a broken 7900 shifter for them to look at. It took them three days to tell me that there's nothing they could do, and then offered to order a 4700 to replace it, because obviously 7900's aren't available new anymore. I suppose I don't blame them. The amount of work they would have to put in to even attempt to fix it is not really worth the time.