Good luck Ferrograph723!
You may wish to look at my thread on restoring a Series 4 I got on Freecycle. It has ended up being quite comprehensive, especially MS660's many edifying posts. I took the machine apart down to its constituent nuts and bolts, recovered it and am currently using it as my bedroom record player amp & speaker. The inside was similar if not worse than yours, so it's eminently possible!
You can find it here.
I replaced the filter/reservoir capacitor the other week, but have still not quite got round to aligning all the tape sections. It plays, but not as well as it should, so the thread is on-going!
I really went wild and recorded all the screw locations and types so I didn't end up with a pot of 'where do they go?' washers and other parts, and so I'd be happy to share the notes I made with you if you need a hand.