I bought the printer recentl;y off a freind so the bed is already pretty torn down with resudue from the past but whenever I try to use the auto delta calibration I get a scan thats off by 6 or even sometimes 8 mm and after poutting crasy big z stops the scan is still extremely bumpy not sloped. Do I need to get a new bed? or is it something else?by phellykz - Fisher