I chased false limit switch triggers for weeks with no success. My solution was to introduce a 12V DC relay - the six limit switches were wired in series and were in the 12V supply circuit to the relay coil. The normally closed circuit in the relay was wired to the limit input of my controller.
Works well. Not the best solution, but for the life of me I couldn't work out what was causing my limit switches to trip - and I tried to be very diagnostic.