I have not tried it yet as the tub is new but I've read that cleaning the tub with "Swirl Away" or something like that could free up the jets.
Doc sells it on his site and he has some customer comments and it seems to really clean out the tub. I did buy a bottle to clean it at 6 months.
Another thing you can try might be soaking a jet in white vinegar - if there's any deposits it could break it apart.