Polaris PB4-60 No Pressure

[DPKJr]

I have a Polaris 280 powered by a PB4-60 booster pump. I went to run the cleaner at the end of last year and noticed that the cleaner was not moving on the bottom of the pool. I turned off the pump and disconnected the hose from the side of the pool and saw that I had normal water flow from the port on the side of the pool when the pump was off, but when I turned the pump on the pressure did not pickup. Normally it would blow water all the way to the other side of the pool. So the pump is running but no pressure. Anybody have any suggestions? Could it be the impeller? Hate to buy a new pump if not necessary. Thanks in advance.