Ricoh Aficio MP 2510 SC 541, SC 542 Errors

Hello,

on our MP 2510 the error code SC 541 has appeared. I've replaced the thermistors of the fuser, but the SC 541 keeps appearing, although I've resetted it by executing SP 5810 in service mode and power off/on.

I've built in a spare fusing unit, a new one, also with new thermistors. With that fusing unit the error SC 542 appears always, also after resetting by executing SP 5810. Toner was'nt fixed on the page before this error appeard.

So I have SC 541 with one unit and SC 542 with the other unit, reproducable.

I've also checked this technical service bulletin: http://www.standleys.com/SERVICE/Bulletins/8025-30/8025%20fuser%20SC%20codes.pdf. The therein mentioned screws are ok.

What could cause the error? Something else beside the fusing unit?

Thank you for advice!

Stefan