I had to replace the tray 2 pick-up solenoid on a M521dn MFP. First, I had to replace the DC Controller due to lack of -24VDC to the main motor (59.50 error) from J2103 pins 7 and 8. Now I keep running into the “52 scanner error” when I try to perform the engine test or perform the copy function. Voltage from the dc controller (J2104, pin 1, -24VDC) to laser scanner motor (J12, pin 4) is good, and voltage from the low voltage power supply (J1811, pin 4, -5VDC) to the laser driver (J100, pin 4) is good. When I initialize (boot up) the device, I noticed that the scanner motor does not “zero out” and there is no beam. If I press the engine test button, the laser scanner motor (mirror) spins, but know beam. I have replaced the ribbon cable between the low voltage power supply – no joy. And this is the second laser assembly. Any assistance would be deeply appreciated.