We have a problem with our Pentair heater. It was working 2 days ago and tonight it will not ignite and the service light is on. All off the lights are lit on the front panel except for the heat light. The manual states that this may be the thermal fusible link, but I bypassed the link and there was no change. Does anyone have any experience with this heater and have any advice on troubleshooting this problem myself? There has been no change in the water flow or gas supply since it last worked. Any advice is appreciated.