We have an older model ADS AF machine that we are placing in our church. It starts to cycle properly, pumps appear to work, it fills and drains but then when it starts to fill again the water does not shut off. If I shut of the master it stops shortly after. I'm thinking its the fill solenoid but wondering if it could be the timer. I've never repaired one before and don't want to waste the church's money on unnecessary parts. Any thoughts?