If you Aquabot stops working, first check the fuse. If its OK, try holding down the "start: button. (Only models with a built-in timer have a start button). If the unit works as long as you hold down the button, then you probably have a bad timer module. You can't buy a timer module from Aquabot (they want to sell you a whole new power supply for several hundred dollars), but the timer (and start button - its only purpose is to start the timer) can easily be bypassed and the unit will work from the on-off switch. I you have any electrical knowledge at all, and a multi-tester,it's quite easy. My power supply came apart by removing 8 sheet metal screws on the sides. I understand later models were pop-riveted - in that case the rivets have to be drilled out (and replaced with screws). Inside you will find: a large transformer that converts 115 volts AC to approx. 33.5 volts AC, and the timer module (black plastic, approx 2"x2"x1/2" thick). Before you disconnect any wires, use your tester to check the power cord, the fuse holder, and the on-off switch, to eliminate any malfunctions with these components. BTW: My on-off switch has its input (from the fuse) at the top terminal, and output at the middle one. The bottom terminal is non-functional, even though the neutral lead is connected to it. So now you want to connect the output of the on-off switch with the positive input of the transformer (polarity may not be for AC but play it safe. Then remove the neutral (white from power cord) from the start switch and connect it to the same input side of the transformer as it went previously after leaving the timer. (I was able to use all the existing connectors.) Plug the unit in, turn on the switch, and you should see 33.5 volts AC at the output connector.

Some models have a remote control and I don't know if this function can be retained if the timer is by-passed, but the wiring of all units if fairly simple.