the pot most likely didn't have anything to do with it, and it is actually my W.A.G. that your problem is related to the guide pin in the bottom of the armature of the forward contactor, and it causes an intermittent bad connection in the "at rest" position of the forward contactor when you try and drive in rev, the fact that the connection takes longer to "make" than it should is where the code 24 is caused. it could be in a bunch of places in that circuit, that is just a w.a.g. with some experience behind the guess