ES720 stapler woes

[vincent64]

When trying to do a staple job, it will give the message, "CHECK STAPLER"
Pull cart out, remove a few from the front, reload cart, it will not try to feed staples.
But there is no message for loading staples like it was empty of staples.
Tried swapping out the staple unit itself, checked connections at the finisher PWB.
Could not find a mode to test function of the stapler unit.
May try the PWB next, any ideas though.

[Mr Spock]

which finisher? On some of the models there is a little (and I mean little) black plastic actuator that determines if there are staples in the unit. If this pops out (and it will when the cartridge is removed) then it will not see the staples in the cartridge and give this message.

[vincent64]

The finisher model is a MJ-1027

[Toshi]

When you changed the staple unit, did you replace the wide white ribbon cable as well? The metal wires inside those ribbon cables can break loose and it can intermittently lose connection