Sounds like you have tried everything already, so it would be a hardware escalation: 1-800-821-2797.
Printer is WorkCentre 7556 with Finisher LX running on latest firmware with no problems.
When I try to connect the booklet maker option for the finisher printer disables finisher tray output.
The options for the booklet unit appear in the printer menus so printer does see the addon.
However if I check error history there is a fold detect fail present. The booklet unit works OK on other printer.
I tried ALTBOOT and forced upgrade the printer, but the problem is still the same.
Any suggestions pls?