I went to National Camera Repair School and...
had to take shutters down to the last screw. Many shutters can get a big help by just dipping the whole shutter in a cleaning solution and then blasting them with compressed air to clean out the solution. This is not the way recommended by the school, but is worth doing for the first step. Ofcourse you will have to lube the shutter and aperature leaves. As one guy said he used a graphite powder, but there are probably better things now. The big problem can be getting those leaves back in. It took me a couple hours the first time I did it and 15 minutes after a while. You might be able to find the old National Camera books. They have long been out of business and the copyrights to the books were bought by one of the authors and instructors but he has since died. I wish we had the internet when I was doing repairs as it would have made so many things easier. Another word of advice. Many of the escapements for slow shutter speeds can fall apart by just removing the screws and you will have your afternoon cut out for you putting them back together. Better to just remove them and clean them as a unit. It would be nice if someone made a .pdf file with pictures and text telling how to disassemble these old cameras. Do a search for National Camera and Camera Craftsman (the magazine they published) to see if you can find how to repair your shutter. Ric.