Used this Apex Ad-2600 DVD player only a few times. Has been
sitting in a box for close to 10 years. Tried it out the other day,
and every type of disc loaded gives the same 'no disc' message.

Cleaned the lens, made fractional adjustments to the pots next
to the lens, but every time it tries to load a DVD, it slowly spins
a few turns, stops, slowly spins a few turns again, and then the
'no disc' message appears.

I have seen the 'no disc' message mentioned on the web with other
brands of DVD players as well, but couldn't find any response as to
what the most common reasons would be for that. Any ideas?