not a Konica Minolta Dealer, got a machine with under 2K throwing C-4520 error code, got the service manual and tried Machine Adjustment/Printer ADJ/ Color Registration ADJ/ Start and procedure completes with Eror 2. any Konica Minolta techs Please help?

It refers to the laser unit
ensure that the shutters are openning
and that the reg sensors are clean

you need to clean then very well low volume machines have this more than higher volume as the toner blowoff blowby seems to settle there