I think its all going to depend on what kind of transport the unit has. I can't see the problem being anything else. It sounds like the laser may be dirty, as you suspect, or possibly something to do with the tray itself. Given the fact that you sometimes get the disc to play after you move it in the tray. I don't know what player you have, but I think it would be a pretty safe bet to try and locate a new transport. If you are not afraid to open the unit up, its probably a part that you can easily replace yourself.