May not be something you want to do, but with a few basic hand tools you can do this yourself. I have cleaned my 35SE a couple of times over the last 30 years I have owned it, for the same reasons you are experiencing. Only tools needed is a spanner, or paper clip bent in the middle, some small screw drivers, needle noise pliers, and denatured alcohol to clean the gear train and clock oil to re-oil it. Remove the film advance lever with the paper clip. Remove the film release lever, screws on the ends, and take off top. Mark the gears (film advance) with a Sharpie so you can assemble them correctly. Remove them and locate the governor under the top plate on the left as viewed from the rear. Use a brush and the alcohol to clean the gear train. There is a little rocker there that runs on a notched wheel that provides the slower speeds. Once clean lubricate it with clock oil (very little needed) and reassemble. This sounds complicated, but it is not. My exposures are still spot on, so the cleaning does not mess with the shutter speeds, thus no adjustments are needed.
