If I hold the laser sled in place, no pressure up or down, it appears to play fine. When I let go the sled speeds across the disc to the end. Made a video showing this:
https://youtu.be/mBwFp1RFvRIWhat the video doesn't show is that it takes awhile after loading the disc for the player to access the disc and when it does it quickly shoots across the disc to the end, just like when I take my hand away in the video.
I read about a Pioneer 503 that runs that motor with +15 volts/-15 volts and if one of those fuses blows this situation occurs. Seems likely to me but so far I haven't found a blown fuse.
I'm just an enthusiast with limited knowledge willing to try things.
Any ideas?