Thanks for the previous feedback... a bit what I thought...
I got the error yesterday again, but as you stated... without a service manual, the provided info is not going to be very useful... and a SM is no public info, so I'm affraid I'll have to wait to find some on Internet, because having a Xerox tech come along for a machine bought on Ebay will probably cost more than the machine... ;-
I could eventually try my luck with an older SM...
Regards,
Philippe