Open Tray Error and grinding noise

a friend gave me his old 360 because he got a 360s. he told me that it wouldn't read discs. I already have one with rrod but the drive works perfectly....when i turn the one he gave me on it loads up normally except for the 2 grinding noises(even without discs). When i put a disc in, the 2 grinding noises occur again, at the same time it says reading disc then open tray.....I have tried the dust remover, the one to keep it from going back to far(laser), the magnet shifter, and cleaning the lens...all were carefully done....NOTHING WORKS....only thing that does is banging on it which i wouldnt prefer as this could cause more damage...the only thing i havent done is tweaked the laser known as pot calaboration. my warrenty is gone also i dont want to solder anything if i can do something less time consuming...and i dont want to flash either but will if it comes to it....so help please