I'm looking for some help on two kcm831 elevator's I have. We have been fighting what I think is a common problem between both cars in this duplex. Has anyone had one car shut down on either a 72 or 74 fault with no other faults logged. I've looked up these faults and it leads you to the inductors on the car top but I don't feel this is where are problem is!! Ok it gets better, remember this is a duplex and one car may have this shut down once every week or every two months or two days in a row with no pattern. After causing several service calls over a period of two or more months the problem goes away and moves to the other car and repeats the exact same sequence causing a series of service calls just like the other! After car #2 takes it's turn it will go back to car #1 back and forth. Just when you think you've got it fixed it will show back up! I've been chasing my tail on this now for a long time with no luck fixing it! I've replaced ADON boards, inductors, changed parameters, grounded the cars because they were not grounded during installation. I've set up the brakes on the MX20 machines and set to 0.002 of an inch pick and the list goes on! This problem has never trapped anyone nor have I ever received any first had reports from anyone seeing it shut down it's just found either just above or just below the floor with a 72 or 74 fault! If anyone can help that would be great, this is kicking my ass!! One more bit of info that might help. There are two other kmc831's in the same bldg that give me no trouble, the only difference is the hoistway setup. What I mean by that is the two that never fail have the machines on top of the main rails and are hospital sized cars. The two that have this problem are 3500lb passengers and have the machines on top of the cwt rails like I've never seen before???Thanks for any help!