Pioneer XR-P470C Mini system CD section duff

Hi,
I've recently bought a secondhand XR-P470C mini system which has a duff CD
section and would like some advice as to what is likely to be wrong with the
CD unit.

At present, the units CD tray will open and close, the unit will change CDs
(3 can be used)
but after going through a check of all three CDs the unit displays "No
Disc". All I've tried so far is inserting a CD head cleaner disc to see if
it was muck on the lens but to no avail.

Aside from the CD trouble the unit and its remote control are working very
nicely and played through my B&W DM-610 speakers sounds fine.

I'd be grateful for any insights you gurus might have on the problem.

Thanks very much

Tony (Hereford)