ive got a playstation 2 that can only read ps1,blue ps2 games SCPH-50003?

as i said it can only read them but not any dvd or dvd game. ive opened it up and cleaned the inside and ive even fiddled with the little white cogs but it still wont play dvd's. im begging anybody out there to tell me what the F£$KING HELL IS WRONG WITH MY B$£TARD PS2. if i dont get word soon im just gunna smash it up and eat the F^&KER because to be frank IM JUST GETTING PI*SED OFF. thank you