So....how does this relate to appliance work and in specific, a belt-drive Whirlpool washer?
Well, the first thing is an enthusiast should know the product they want to work on. Know it in how it is supposed to operate, what is normal and what isn't. Either that or be ready and open minded to learn as you go.
Then, yes indeed, access to parts is always good, or as Ben said, having the resourcs to find and keep a good service person willing to do the work.
I ABSOLUTELY LOVE to restore these machines when the mood strikes. If not in the mood, it can be a royal pain. Acquiring them is the fun and easy part. Keeping them running is not always easy, and if I couldn't do the work myself, I can see where another Mustang-like restoration would ensue that would drain my enthusiasm.
The best part of working on appliances, especially ones which I have loved all my life in all their forms and variety, is envisioning a project, and making it happen, and not having to wait three years while the interest level turns into a big pile of stress. Echoing what Ben said...this is something I can do myself. It is often more fun to take a piece of crap and make it into something desirable, at least for me, vs. finding something mint and merely collecting it.
I agree with what John said too -- restoring that '66 Whirlpool, or any washer like it, could take some time, time to locate parts, and time to do the work. Taking the machine apart, removing the time-worn offending parts and replacing them, especially the bearings and seals, will eat up time and money if you're paying someone to do the work.
For you 1966_Mustang, since I think you already are restoring a car, you probably know the drill. I would say to take your investment in this machine, try to work on it yourself, learn, and then do what you can your self. This is cheaper and more satisfying to someone who knows what restoration is.
I can help locate parts. I may have something, and I may be willing to share. If not, there are resources here to help. The best thing you can do is to get to know people here.
Good luck!
Gordon