You can clean it yourself. Check online for a manual. I didn't print the 40 some page one for the 1978 machine I cleaned - just read what I needed to. Work on a very large towel with a muffin tin for removed screws and remember where you took them out. I scrubbed the exterior with Simple Green and dried it well, then cleaned the inside with oil. If a spot moves oil it well. If the book calls for grease, get some - don't use oil. Take the bobbin area apart and get all old lint and thread. Toothbushes and lint brushes get a workout, but it's easy to do.
I don't know much about a 1966 model - the newest one I use for quilting is a 1956, but if yours is working well, then put the money aside and enjoy your vintage machine. There will be machines available when you need one. I might watch Craigslist for a backup, but avoid a used plastic machine.