My CD changer has started having trouble playing cds usually cd 4-6 and the tracks that are later on those paticular CDs, skipping can be intermittant, sounds like a dirty lens, Ive never had much luck with cd cleaner disks - on pc cdroms anyway, whats the best way to go about cleaning it.

Luckily the changer is reasonably accessible, try the cleaning disk and if it doesnt work then you can try this but at your own risk. Remove the magazine and look through the slot where the magazine usually goes, you should be able to make out the mechanism and the lens itself (A torch may help). Using a lint free or microfibre cloth, rub the cloth across the top of the laser dome and this should remove any stuborn small particles.

Would it be worth trying a can of compressed air first?