If anyone has a duplex Dover oildraulic job, here is a great tip that will save you a headache . If you ever have to replace the power card make sure you shut down BOTH cars, then replace card and then turn on power to cars, if you don't you risk the possibility of ruining more than one card in the rack. Unfortunately I found this out the hard way, I ruined 8 cards while troubleshooting a duplex by replacing power card of car I was working on while other car was on. Only after reading oildraulic manual from front to back did I see this info in the manual. I shut down both cars and replaced all board turned both on and no more troubles, Talk about a headache