I have a couple of Leica Ms and of all of them, my favorite has to be the M2. However that M2 is also the only mechanical camera in my possession that is in need of overhauling. Clean, lubricate & adjust as they say it, or simply CLA. Doesn't take long to do a search on the Internet before I stumble across a supposedly nondescript shop in Chungmuro (충무로) that came recommended. GPS coordinate is approximately at 37.562063, 126.990041
To get there, take line 3 orange line to 충무로 station and get out at exit 5. Continue straight towards Myeongdong and one you pass a big tower called Kukdong Building, turn right and immediately turn left on the next small junction. About ten meters later on your right will be a small camera shop called Yeongsang 영상 Camera. Go up to the second floor and there is a black and white photo developing shop. In a small corner of the shop, the old man there will CLA your mechanical camera.
Mine took only 2 hours. About the time it takes to develop a roll of film and cost a reasonable 100,000₩. The finder all clear now an all mechanical parts humming along, it's cheap and at the same time fast. I was initially expecting a week before pickup. Who knew I could browse the camera shops around the area and pick it up on the same day.
Highly recommended shop. Thanks to rangefinderforum.com for the initial directions. Shop opens 10am to 7pm. However the owner is sometimes downstairs in a used camera shop.