I'm having an issue with our 2004 VF-3. The proximity switches for the shuttle in and out are acting up. The switches test fine and they supply the correct voltage back to the I/O board. Though on the I/O screen they both say 1. The weird thing is that if I open the door to rear panel and wait a minute they will work right, but if i close the door I can watch the 0 turn to a 1 on the I/O screen and it will fault out. I installed all new fans and the cabinet filter thinking it was a cooling issue. I also replaced the I/O board. Still no luck. Any help would be greatly appreciated.