Enter the Ricoh Repair Guy. Shades of "Twas on a Monday morning, the Gas Man came to call..." I don't remember exactly why we called him - I think certain sizes of paper were sometime sticking but because no-one in office had the time we found a Ricoh service center and had a tech come in.
After he left the printer did not have the sticking paper problem but the magenta color was ghosting - or offset - by quite a bit, rendering every color print unusable.
Called the guy up and he says he will order a part to fix it.
Called the guy a week later - he forgot to order the part. But it will be about $600. He says something about the waste drum for the red being full. He either doesn't know what he is talking about or doesn't want me to know - this print HAS no red, it is CMYK. He suggests we order the part ourselves from Ricoh.
The nearest part I can come up with that he might be talking about is the Color Drum Unit which has three parts for CYM and can be bought for around $400 online. But I'm not really satisfied with this response so I do some more digging.
Finally I find the Service Manual (if you need it let me know...) and read this:
My guess is that the tech did not know he was supposed to run these after messing with the printer.4.3.3 COLOR REGISTRATIONLine Position AdjustmentThe automatic line position adjustment usually is done for a specified condition to get thebest color prints.Do the following if color registration shifts:Do “Forced Line Position” as follows to do the forced line position adjustment.1) First do SP2-111-3.2) Then do SP2-111-1.To check if SP 2-111-1 was successful, watch the screen during the process. Amessage is displayed at the end. Also, you can check the result with SP 2-194-10 to-12.Image AdjustmentYou should also do the line position adjustment at these times:After you transport or move the machine (you should do the forced line positionadjustment if you install the machine at the user location.) if the machine ispre-installed at the workshop and moved to the user location,When you remove or replace the motors, clutches, and/or gears related to thedrum/development/transfer sectionsWhen you remove or replace the image transfer belt or laser optical housing unit
With some more digging online I found the way to access the C820 Service Mode:
Press up and down arrows simultaneously for 5 seconds then press ok.
SP2 is to be found under "Engine" and then "Drum". Then choose 111 and then 003 as you might expect, and so on.
My results for SP2-194-10,11,12 were: M1,C1,Y1 respectively where 1 means completed successfully.
And the test print came out looking great!
I hope this helps someone else out there...