The reason I asked if a polarity servo was used, the power leg is shared by the servo and the logic circuit. A short or high current draw on the servo circuit could show as loss or dimming of the LCD and/or glitching the process of the logic. Since this is not the case, disregard.
The shielding on the S1/S2 would not have anything to do with the motor running to the physical end stop, but it could produce count errors. To address Brett's shielding suggestion, it is valid... Personally, I would never use a twisted pair over and distance for noise rejection with a DC motor and DC reed switch circuits in close proximity. A twisted pair is not effective at broad frequency rejection. I would connect a scope and see if any noise artifacts are being introduced into the S1/S2 switch cycles from the running motor.
I am willing to accept that there is a problem with the software to cause a run to the limit switch, but approach that suggestion based on the thousands of units placed into service, years of technical support and customer feedback. I believe that there is something unique to your system that is causing this problem.
If you wish to troubleshoot, we will try to identify and resolve this problem. I would appreciate if this effort involves real testing processes. This thread may need to stay open for a while, as the information may need to be gathered over time to put the puzzle pieces in order. It likely necessary to answer these questions and address new information over time. I would appreciate if you provide as much documentation as possible. I.E. photos, screen captures, scope readings.
Let's start with these questions:
1. Is the ASC1 used stand alone or controlled via DiSEqC commands from a STB? If stand alone, using the front panel buttons or the RCU? If not using the RCU, have you tried disabling the RCU IR function with the front panel button?
2. If the RS-232 cable is used to read / write satellite lists, is the cable disconnected from the ASC1 when not in use?
3. When the actuator runs to the limit switch, do you find that the 0000 reference now offset (reset) to a point outside the range of the limit switch settings?
4. Does the run to the limit switch occur on a specific satellite in the list?
5. Is your dish grounded and is the dish ground bonded to the structure ground? If so, how is the dish grounded? How is the dish ground bonded to structure ground? Is the ASC1 AC plug ground verified to be connected to structure ground?
6. How Many LNBs? What is the power source of the LNBs? Are all LNBs powered at all times? Does the ASC1 control polarity selection or another device? LNBs total running current draw? LNB current draw at start-up? Inline polarity and or band switch? Type of switch? Powered or passive?