Error E7-20 SHARP MX-C402SC

Ive got a MX-C402SC from Sharp, and it keeps throwing the error code "E7-20" Call for service. Every time I power cycle the printer, it starts working again fine for a few print jobs (The bigger the print jobs, the quicker it will throw the error again.) This error code refers to "LSU-Laser Detection". To fix it you need to "Use SIM61-1 to check the operation of the LSU. Check or replace the LSU control PWB. Check connection of the LSU harness. Replace the LSU."

My questions is this: What...

Error E7-20 SHARP MX-C402SC