I know this is an old question but maybe someone else will have it. If the gears are grinding, then it is a problem with the toner cartridge. The plastic gears in the unit will skip teeth if they are hard to turn in the toner cart. So replace those toner carts that are making noise. Put them in one at a time and you will find which ones are stuck and causing the problem. Also, DELL has never blocked 3rd party toner on the E525W. It has very affordable toners. If your carts are 3rd party and giving errors, there is a menu option "use 3rd party toner" which will disable the %toner remaining, and it won't complain at all anymore. But my 3rd party toners all come up as official dell, even with the last firmware updated they put out.