Panasonic SC-HT520 System "disk dirty error message dvd" Questions

dirty... my panasonic home theatre model no. Panasonic SC-HT520 is creating problem with some disk. after lots of struggle in reading it gave up, two days back one of my disc (Verbatim dual layer disc

...dirty, or the drive itself is faulty. Try cleaning the lens with a lens cleaning disk, if this does not work, return it for replacement (If it is still under warranty), or take it to a repair shop to ...

...disk, I also didn't know the system should be thoroughly cleaned periodically, (not that I know how), and have also been told that if I take it in for repair, I could be overcharged, told something ...