I have an Alpine CHM-S630 6-disk CD changer that is giving me grief.

The unit selects each CD properly from the magazine, but as soon as it
loads it into place, the optical sled slams out to the full extent of
the limits of the track, out to the extreme edge of the CD diameter.
It never appears to go to the center of the CD, and it never takes a
read from the disk.

After the sled hits the track limit, then for about 2 seconds, the
worm & roller mechanism keeps trying to push the sled out through the
side of the case, resulting in a horrible grinding noise as the
plastic block on the sled strips itself against the "worm" screw,
since the sled can't move any farther.

After about 2 seconds elapse, the unit gives up and stops trying to
push the sled past the limit of the track. Another 2 seconds after
that, the unit gives up on spinning the CD, and the CD comes to a
halt.

This happens every time the unit loads a CD.

I've tried cleaning the lens on the sled, but it doesn't seem to be an
optical problem. It doesn't seem to be a mechanical problem, either.
The worm & roller for sled movement works just fine - the problem is
that for some reason, the unit is telling the sled to slam out past
the limits of its track. I'm stumped.

Can anyone point me in the right direction for a fix?

Thanks.