I have seen several comments about Aqua Hot not firing. I fought that for several years. I found many repair people that are good parts changers. The coil in mine would pass the test every time, then I realized If the cover was off it would fire every time. Since the cover is not connected electrically the coil was getting hotter than normal. I changed the coil and it has fired every time. The coil is expensive so I had not changed it because it passed the (coil) test.