Heidelberg QMDI-46 Classic paper travel issue

Hey everyone, got a question about our QMDI Classic (15 mil. imp.). We've encountered many of the usual issues over the years and are very familiar with the quirks of the press, but now we have a new problem.

The press will idle and feed sheets without impression, but as soon as impression is turned on, the press feeds three sheets before turning impression back off and then slowing to its usual stop.

The press is not reporting any paper feed error indicator lights, and doesn't record any unusual or helpful diagnostic codes. The pile height and angle are within tolerance, and the sheet length system is reporting the correct length.

There are no dropped sheets underneath and all electric eyes are clean. SF 18 and 19 (sheet travel monitors) are turned off. We do not use the double-sheet detector. We have reseated the X7 plugs in the cabinet (a continuing problem). When we have the X7 plug problem, the press exhibits similar behavior as it is now, but one of the compressors will come on and stay on, and it's not doing that now, so I am inclined to rule that out. We've also checked all the feed mechanisms and troubleshooted the switches and sensors in that area and they seem to be working as expected.

The temperature of the chiller is where it should be (~20-degrees C). The air pressure seems to be correct and the compressor doesn't run more than usual. We do not use the automated wash-up or plate vacuum systems. The press was running fine yesterday before this started happening.

I think it is a problem in the electrical cabinet or the electric eye under the press. What do you think? Any ideas are appreciated!!

-Noah and Steve at Pronto Print in Medford, Oregon, USA