20 years ago this was our everyday world. You have to play detective and eliminate problem areas from your thinking one by one. A lot of times when a Dover was stuck at a floor it would be from what we called a CS lockup. The CS relay should pulse in and out, but things like a door lock bouncing would cause it to pull in and stay energized. You may want to look at that circuit closely. Also if you have worn leveling rings on the selector it can create problems. A wire relay checker from SEES was also an invaluable tool for checking out Dover Relays. When you pull a relay out be sure to wiggle it from side to side and not up and down, this causes the base pins to get bent. Good Luck.