I have a Sony CDP-302 player
this is an old, ~1986, high end player.
It playes very well --- as long as it is tipped to and angle of 45° or
greater on either side. Not 40°, but 45°, maybe 43°. I measured it.
If I tip it from 40° to 45° it will start working. No bumping or
jarring required.

If it is flat or tipped to any angle front to back, the spindle motor
won't operate. The spindle motor circuit doesn't get any drive
signal.
I traced it back to the electronics board and something is shutting
down the generation of the signal. The problem is on the CD carriage,
because I loosened the electronics board and tipped them seperately.

The spindle motor is an open DC type. Coils are on the PC board with
the magnet attached to the bottom of the spindle. NOTHING appears to
be loose or jammed. All micro switches seem to be operating in all
positions. It worked intermittently in the flat position for a while.

It is suppose to spin the CD on insertion or power on and read the
TOC, then stop and wait for the play button. It does this only when
tipped at the proper angle.

I don't have a schematic, but what would be position sensitive to
shut
down the drive signal?

thanks