I have a CS 5050 with the DF-710. I'm getting C-8230 code. The stapler would do double staple fine and jam on corner staples. It tries to staple four times. Now it just tries to staple with no staple cartidge installed and gives a C-8230. We replaced the stapler head and finisher MPCB. Yes, it's the correct P/N, we have old style finisher and used the proper parts manual. Firmware was also current. Ohmed out the grey wire harness on the stapler head, it was OK.
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Good luck and may the schwartz be with me.

Did you check continuity in the harness while moving it? Sometimes there are little cracks in the wires that don't cause problems until they are moved a certain way.

Yes we test the wire harness and ribbon cable also replaced main PCB e prom and connector PCB

I've got a 4050 with a DF-710 doing the same thing. When you do the two staple book type staple it is fine. When you do the single staple, it rotates to its correct position, then drive 4 or 5 staples into the set. I have replaced stapler assy, finisher main board, ribbon cable and junction board on the side of stapler assy. Problem started as the stapler not recognizing the stapler cartridge. Even installed new cartridge assy. We have checked the gray harness, ohms out ok as well. Tried another main finisher board from another machine, same symptom. Hooked another finisher up to the 4050 and it works fine. Running out of ideas and really puzzled.

The gray wire harness is bad, the wires inside the coating are broken, when the harness bends then that is when it fails.

caught it today. There is a bad spot in the harness. The left single staple and the double staple are fine. it is only when it rotates to do the diagonal type staple. Ordered the harness today. Thanks