Hello Good Day, I have a milenium Sand Filter with a multiport Valve and it started leaking (Slow Drip) out the backwash Valve. I replaced the multiport Valve with a brandnew one and all gaskets brand new. We found out that it only leaks when the filter is on High and not low, Also now noticing that in the Backwash Postion not much pressure pushing that water out, in rinse postion as well? Lines are hooked up right we doubled checked that. Please help!