Those Sony 757 deck internals look a lot like Panasonic AG-1970/80 type units!
12voltvids has serviced this model before. https://www.youtube.com/watch?v=BWuk6wOpazc
This is essentially an ancient mid-grade VHS VCR. It's honestly not worth the effort to fix, and just use another VCR for FF and preview if needed.
When you open up decks this old, and start tinkering, it can break worse. That's happened to me too many times, on decks newer than this, and I know what I'm doing on those units. So beware.