Mike, thanks for the offer, have a spare now, I'm hoping the "compatible" one will be the last one needed for a long time.? An old one is likely to have the same problem with the silicone fluid.? I went with the silicone after replacing the corroded and rusty brake lines and master & brake cylinders.? The switch has failed a couple of times over 30 years, though the vehicle hasn't gone far in that time.? Probably the regular brake fluid would have been fine if I drained and replaced it periodically. ?