Cavitation Issues

[etrain0025]

I sent my prop off to have it refurbished and when I got it back and put it on the boat I started having major cavitation issues. When I go out by myself I have no problems but when I add anyone else at all it doesn't grab. It takes off and then when it hits 22 mph it just spins. I sent it back thinking I had broken it loose from the hub and they sent it back saying everything was okay. The boat repair guys told me to drop the jack plate but don't see why I should have to do that if i've never had issues in the past. They are telling me Im having some kind of weight issue but I haven't changed anything. I dropped the jack plate about an inch which is what they suggested and its getting a little better but is still not fixed. Should I just keep dropping the plate down? What will happen if I just drop it down all the way? What am I missing? I have had 4 big guys with over 100lbs of camping gear on board and not had any issues in the past I don't understand why when I put 110lb girl on board it throws everthing off now. Anyone please help.