A very serious and common problem with Ricoh Aficio MP 2501 SP is the System error SC 520-00 . When the registration motor is rotating but does not rotate as it should. The cause of this would be Motor Lock or Defective motor driver.

That could be the case but before you start searching for a new motor or a spare part, you should alwways check some other thinks first.

The first think to do is to make sure that the error is not sympomatic and the error could be erased from the system machine if you reset the machine status from maintanance mode .

So some process to do :

1. Go to maintanance mode by pressing Clear (yellow) button, 1 0 7, and press and hold Stop (orange) button for 5 seconds. Go down to find sc and reset the main function . then you should restart the machine from the main switch.
2. Some suggest that you should cheat the machine with the side door open
3. If nothing happens, then you should start searching what could be blockin the motor from running as it should be. The main motor is being tested every 20 milisecondw to check the proper functionality. If something is blocking it, it generates sc520 error code. So you should check every component that could be blocking it. The first to check would be the Drum Unit or fuser. It could be blocked by something or by excessive toner inside Drum Unit. The Fix is quite easy for technicians. They should open it up and reduce the toner inside the drum unit that is causing the motor to turn slow. That’s it.
4. Another check could be the defective fuser. You should check for defective rollers or debris inside

That’s it. This can save you a lot of money and make your machine work ready.