SM74 feeder sudden stops

Hi friends...
I'm with a problem in SM74 5+L from the year 2006.

What happens is just this: just feeding sheets without printing, i have no problems. If i try to print, no matter which unit i choose, the feeder stops after the third sheet is feeded into the machine. No errors are shown on cp2000....

Any hint? I just don't understand what's going on...

 

Does the feeder stop or does the press stop also? You also say its not an issue when just feeding sheets? Can you get up to 15kiph just feeding sheets with no issues or have you just run a few sheets? When you say its the third sheet that trips the feeder, but is it usually the third but it has happened when it was the 4th or 5th sheet also? Kind of unusual to have that kind of consistency with feeding problems. Have you tried different thickness stock? have you tried to take machine off of auto sheet arrival and manual retard or advance the sheet? One common issue with SM74 is that the feeder timing can be moved and very difficult to get back due to a seized adjustment sprocket. Make sure the sheet is arriving at the headstops around 300 degrees or very close to it. Also, visually check the headstops and make sure when they come back toward the feedboard that they rest against the feed board with pressure. Use a thin sheet of paper and put it between the head stop and feed board and inch the press. You should feel the head stop come into contact with the feed board. Also, check to see if the cam follower under the feed board in the center is in good shape, also very common for this cam follower to go out on machines.

 

Thanks for your help...
My costumer drived me crazy by phone, then i tried some help here and today, when i looked into the machine i found a preset counter for three sheets...the machine was stoped during two days because of this.

The operator keeps telling me that he did not made that preset...
I do not know what to say, the machine is working normaly..

Sorry for this peculiar moment....thanks anyway, because your reply will be usefull for other issues...