I am currently working on a SD-511 saddle folder for the FS-534 finisher. When ever half fold or booklet mode is used the folders Tri-fold knife assy. moves and catches the folded paper before it can exit causing a crash in the folder. When ever the Tri-folding mode is used the Tri-fold knife assy. moves too early before the half folded paper is in posistion thus causing a jam. If I manually move each assy. by hand I can make half fold and tri-fold perfectly. If I completely remove the Tri-fold knife assy. from the folder, the half folds and booklet folds are perfect. All the technical info that I have on this (Service Manuals, field service and theory of operation) don't give enough info. on the timing of the Tri-fold knife assy. Does anyone know if the Tri-fold knife assy. is even suppose to move at all when making half fold or booklet copies? Is there any special firmware or a technical bulletin regarding this issue? I have confirmed the operation of each mechanical assy. as well as all the sensors in the SD-511. Any suggestions other than the SD-511 control board? It's like both knifes are operating near the same time causing crashes. By the way this folder/finisher is mounted to a C754. Already upgraded firmware. Any info would be appreciated. Thanks