OK. Thanks for your discussions. Assuring in some sense. I was looking at photos of used cranks for sale and found that they mostly had the same appearance as mine, so I became less concerned about the coloring.

As the servo motor had stripped out, I did find that one of the rc valves was binding a little when moved by hand. It did not seem too serious, and after moving it back and forth several times with a little bit of lateral pressure on the shaft, it became quite smooth.

However, I must suspect that it froze up enough to cause the cable to stick, thus stripping off the plastic teeth of the gear in the servo motor. So... I will at least pull the cylinders to find out what the condition of rc valves, pistons, cylinders, etc., actually is.

And I received my new MC21 Service Manual in the post today, so I am ready to get down to it!

http://xn--qckst9n.com/