I'm kind of a tinkerer and enjoy taking apart cameras. I have no formal training, but have had pretty good luck. There is tons of information available online. If it doesn't work out with a particular camera, it becomes a good source of screws and parts, either for me or someone else. One of my earliest projects was assembling a working Petri Color Corrected Super 2.8 from two non-working cameras, including an aperture from one body and the shutter blades from another. I have less experience with cloth focal plane shutters, but only because I haven't needed to really tear into one yet. When I do, it'll probably be on a Zorki 4 or Pentax K1000 body, either of which cost me less than $25. For what I've purchased most of my cameras for, spending $100 on a CLA is not worth it and if I can, I'd rather do it myself.