Just revived an old Ricoh SG7100DN, the SG3110DN, SG2100, SG3210 and others are very similar printers, so this information might be of use to anyone wanting to repurpose one.
I washed out the system, but purging is probably advisable if you are changing ink types.
Info here
https://wyliecoyoteuk.wordpress.com/...-service-mode/
The newer Sawgrass printers have different firmware so not recommended to try it with them.