You need to tell us what the pressure gauge is reading and do you see any air bubbles in the pump basket chamber or coming out the return jets? You could also have a gunked up impeller which would reduce the flow, suction, and pressure.
Before doing the next step MAKE SURE THE PUMP CANNOT START by unplugging or dumping the circuit breaker. Don't rely on a timer to keep it off. Fingers are at stake. Open the pump basket and reach into the hole at the bottom of the chamber and right behind it is the impeller. See if there is anything tangled in there and if so clean it out with a hooked wire or something.
Get back to us and we'll pursue further.