I repair original and repop air grabber switches. Most of the time the three nubs on the back , where the vacuum hose hooks up to, are cracked and or broken off. This will cause an air leak. After disassembly for inspection. I machine new nubs they are heavy duty and better fitted to the air lines. These are then inserted into the body. I then reassemble and test the switch with a hand pump and two vacuum gauges. All this and a one year warranty for $100. Shipping included to the US.