Re: need info for vintage overhaul
You have a few things to watch out for with your Conn 10M, so be very careful who you take it to.
First, your 10M, if it is a 1947, has rolled tone holes. With the rolled tone holes, the pad height is much more critical than with drawn holes, and the height has to be set perfectly, otherwise some pads will leak or sound stuffy.
Another issue is the locking set screws. They can be a pain to get out after they've been in there for a while. They are extremely small, and the tend to strip out easily. Your tech should take precautions to keep these screws from stripping out; like spraying WD 40 on them. Also, make sure that they put the set screws back in. I just happen to have a few of these screws on hand. They are very hard to find anymore. If you should need a couple, let me know.
Are you having the horn relacquered? I wouldn't replace the springs unless they are broken. I would start with a good cleaning, remove any dings/dents, and check the tone holes to make sure they're level. They're probably close enough. If not there are proper ways to level them. DO NOT LET THEM GRIND ON THE TONE HOLES! Then, replace the pads ( I prefer metal resonators, but the plastics are ok too), corks, and felt. I've had my 10M relacquered. The guy I had restore mine does pretty good work. He's very careful not to apply too much lacquer and he bakes the lacquer to cure it.