Thanks. So I guess my next step is to take the top off the filter and see what is going on inside. I'll have to cut some plumbing, so I need to head to the hardware store first. In the meantime:

My "after backwashing" pressure runs about 10-12 psi. Does that sound about right?
My filter is the Hayward s-244T with effective filtration area of 3.14 sq ft, a filtration rate of 20 GPM/sq ft, Filtration and backwash design flow rate of 62 GPM, maximum working pressure of 50 psi; holding 300lbs of sand.
My Pump motor is the 1 HP A.O. Smith 1081 design ST1102 single speed motor
Are the motor and filter sized right for each other?