Hi Norman.... I wouldn't normally comment on a post like this - bit out of my normal area - except that I recently recovered some contactors off an old lift switchboard that exhibited very high resistance on some contacts. Out of curiosity I took them apart and found the contacts caked with black sooty gunk. I cleaned them with a wire brush and (when they were very pitted) fine emery paper, and they were very much improved. However I wouldn't recommend this as a paying proposition - it was very fiddly and for the price of contactors, I'd go buy a new one in a commercial situation. I am curious - (a) is this a contactor that has seen a fair bit of use? (b) were you seeing those voltages on or off load (what sort of load?) and (c) do you have a new contactor to compare with?As Rick says, especially if one pole is better than the others then you've probably got the same problem - accumulated gunk from years of sparky operation...Cheers / David