It started to get noisy about 2 weeks ago...I just drained and re-filled tub, now it's real (loud) noisy and the output is really low (no push to it)
any advice will be welcome...this is a leisure bay tub about 10 years old...

Remove the suction hose from the circ pump and let water run through it backwards to ensure there are no air locks.

If no help then replace circ pump. They do wear out.

how do you get it to run backwards?

You don't do this with the power on.

Remove the suction hose from the circ pump.

Hold your finger over that hose... so it won't leak too much.

Water should flow OUT of the input hole on the circ pump.

And it should flow quite freely.