Seems now days all we hear is bad, but there are a lot of wonderful folks among us. I have way more photo equipment than I could ever afford, my youngest daughter gave me a nice enlarger with lens and other items. In a conversation that started about hand guns and ended on film cameras a total stranger give me a Yashica A and a Rolleicord III, both are in good condition and make good photos when I don't goof. Also I have received a fine Nikon FG from a forum member, it is now loaded with film. And when the temperatures get out of the 100's it will be in action.
Hope I have not strayed totally off topic, just love the camera your with.
Having a CLA on your M3 would be a good place to start. I would recommend Sherry Krauter ( www.sherrykrauter.com ) for this. She can also advise you about repairing the hotshoe or replacing the top plate, if you want to have that done. You might also want to have Sherry inspect the lenses to see if they need any work.
Sherry K is a very good repair person. I have used her and I also have used
16 Fairview Road
Canton, MA 02021