CD PRO malfunction

[evetsfrance]

My four year old Philips CD PRO stopped reading TOC after a month or so of inactivity. I could find no help on the WWW so I took it to bits and cleaned the sled rails and laser lens. No improvement. It looked as if the laser had died so 250 Euros for a new transport - not very good for a high-end unit legendary for its solidity.
With nothing to lose I gave the lens/laser assembly a vigorous poking with the blunt end of a pencil.
Result - works perfectly. Presumably dust or grit had got into the works and jammed the focus mechanism - but even before poking the laser assembly did a vigorous up + down when the lid closed switch was operated without a disc in place. Anyway a happy ending. Any explanations from officianados ?