psx 2 probs

[DEBBIE 2]

Can anyone help i had my psx2 chipped about 18 months ago for about 6 months it was fine. then it didnt like playing compact disc based games like boot disc just kept saying disc read error it played dvd games ok but now it will not play all of them i have tried using cleaning disc but makes no difference i cant exchange it with sony as serial no has come off back any ideas please

thanks debs