Received the replacement head drum belt from eBay, so now we can dive in and do the belt swaps. As I soon find out, it is not an easy thing to do! My camera died and corrupted a video file, the only major thing lost was putting the capstan belt back on (it retained its shape, so I cleaned it and did not replace).
I'll say now that I was able to remedy the issue of the unit not powering up: sprayed some Deoxit into the power switch and she fires up now! The machine struggled to effortlessly play the tapes I threw in; eventually, it would either reach an auto-stop because it was struggling too much or outright eat the tape. Nevertheless, next I'll tackle getting this to display properly on my test gear (this machine is coax-only and PAL, and my CRT can only do NTSC) to see what we have.