Last year, I noticed a little bit of water seeping out of the top of the valve on my sand filter. This year, I assemble the filter and valve, start the pump, and the valve is leaking to the tune of about 2 gallons an hour.

The water is seeping out from under the handle while in the filter position. I haven't checked to see what it does in other positions. Is this a common problem that can be fixed with, say, an o-ring or something? I don't have the original paperwork on the valve, but have found several places that sell parts for it. I don't mind replacing the whole valve, but would rather not, if possible.

Any comments appreciated, thanks.