Tore it down this afternoon for a complete clean-and-grease. The brake pads on the reels have deteriorated somewhat, but it still stops fairly well. At least everything's running quietly now!
I was pleasantly surprised with the sound quality from the built-in amp. It's monaural sound, but the fidelity is fantastic. I tried out some pre-recorded jazz tapes, and was blown away. After playing for a few hours, I thought I'd hook it up to my Magnavox Astro-Sonic console stereo and see how it sounds in stereo. The tape deck has a jack on the front panel labeled "stereo output", but it's dead. There's no audio at all coming from the output jack
I'll tear back into it later and see if I can figure out what's going on with the stereo output. I would like to find a service manual (or at least a diagram) for this machine.