We have a Polaris 380 that is about 3 years old. It connects to a port in the pool which when not in use serves as another return. That port also gets output from a booster pump meant to power the Polaris. The booster pump is about 20 yrs old though. It has always worked well but this year after uncovering the pool and getting it clean and ready to go I put the Polaris in for a regular weekly touch up and quickly noticed there was a problem. without the booster pump the Polaris moves very little but it never did move much without it before. Now however even with the booster pump on it moves very slowly and the tail just drags behind it. In the past the tail would swipe back and forth pretty vigorously. I examined the screen in the piece where the Polaris hose connects to the return and it was dirty so I cleaned that but it did not make much of a difference. The booster pump turns on and when I check the flow with my hand at the return without the Polaris connected the booster pump does increase the outflow so its working. My question then is which component is the problem, the Polaris or the Booster pump and how do I figure that out? I could buy a new pump but I hate to spend a few hundred dollars only to find out that wasn't the problem and the same with the Polaris. Thanks in advance for any help you can give.