Sover Wong is the ONLY person to trust.
I had the Morton Grove, IL guys overhaul my F and F2.
When I sent them to Sover, he completely dismantled them, and by his photographs it was evident that really NOTHING had been done to my cameras. Money spent in IL was just flushing it down the toilet. They even had the gall to put new foam over old, without removing the old crud first.
Old foam grows fungus.
Old foam on the prism will eat away the prism silvering.
Sover is the ONLY person I've ever found who will completely dismantle, clean, and reseal / relube / adjust your shutter to be within 1/4 f/stop accuracy. He will provide you with photographs to show the condition of the camera as he works on it, and you will have an EXCEL spreadsheet at the end with actual measured speeds BEFORE and AFTER the servicing.