I'm NOT of the "Old camera not worth repairing, another old camera can be had for less money" ilk.
That may be true, but then you still end up with an old, dirty, out of adjustment camera, that works marginally and could fail at any time.
If you find a deal on a nice camera with one or two mechanical problems, they can probably be repaired (electronic problems more of a gamble). Send them in to a competent repair service and you get back a fully working, adjusted, cleaned, and light-tight camera that will probably be good to go for many more decades.
Even if you buy from KEH, they do not service the camera prior to selling it, they won't, even if you ask. I have had cameras service by them and they do nice work, but the cameras they sell are not serviced before the sale.
I can recommend Garry's Camera Repair. Very fair prices, excellent turn-around time, and quality work. I've had multiple cameras serviced/repaired by him and been nothing but pleased in every case.