Is it the o-ring around the motor housing or the smaller o-rings inside the aqua stop valve? If its the large o-ring on the housing, there is only two reasons it would fail. The o-ring is not seated properly, or the filter is clogged. Try this:
Disconnect and remove the filter, and break it down.
Pull the new o-ring off and
lightly coat it with silicone lube, then put it back on.
Take
all the media out, including baskets, put the filter back together (make sure the o-ring seats properly. Press down on the motor while closing one latch at a time), fill with water, and set it up as you normally do. You could also rub a small amount of lube on the two small o-rings on the aqua stop valve.
Once you get it running, check for leaks. If it's not leaking with no media in it, then something in the media is clogging it. If you are using polywool in the lower basket, for instance. To much will cause it to clog, forcing the water to run up outside the motor housing and leak out by the handles.
If it's still leaking with no media, it's probably the smaller o-rings or even the o-rings inside the aqua stop valve. Is it hard to lift the first small handle on top that cuts off the water? If so, I would just buy a whole new valve.
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