Stephen,
are u sure u arent mistaking the noise produced by the optics for a
mechanical grinding sound?
If somethings impeding your spindle motor from attaining adequate rpm
the cd would spin and then give up and stop.A simple test to gauge the
problem....try playing track 7, if u can play later tracks then it
could be a spindle servo problem(likely mechanical. Can u hook up an
oscilloscope to rf out and observe the waveform and amplitude? If
amplitude is low you might be able to tweak it by turning the preset at
the back of the block a bit.
The loose belt could be a sled motor belt, see if assisting traverse
motion with a prod enables u to lock onto a track for a few seconds.
Jango.