I know you have been using Rolleis long time but if the problem is just advancing the film after frame one are you sure it is not accidentally hitting the double exposure button when you put a roll of film in? I know I was plagued with that for awhile, something in how I held my camera putting in a roll of film I tripped that double exposure button.
Other than the guys usually mentioned for repairs, (Harry Fleenor at Oceanside camera repair or Krikor in New Jersey, I hear that Paul Ebel is good:
Paul Ebel Lens Services
420 21st St North suite #2
Menomonie, WI 54751
651 335 8759
Not in the GTA but not that far away.
Good question, I will have to search google for an owners manual and see where the double exposure button is located and see if I'm hitting it. Worst case I'm off to Camtech in Hamilton (aka the Hammer) to have them look at it. As much as I want to send to Harry Fleenor or Krikor, I will leave that as the real last resort. My brother lives in NYC I can have him deal with the logistics.
"Life moves pretty fast, if you don't stop and look around once and a while, you might just miss it."