I looked at my proportion valve today to see what it looked like. I thought about buying a new one till I seen the price. So I thought I would test it. I touched the bat. to it and nothing. I don't really know how to test the switch. Anyone ever test one of these animals. I blew air in two of the lines that come from the master cylinder. Air came out the rear line hole but no air out the front holes. Air does pass through the front holes straight through the block.