The pump is old (maybe 18 years), but worked OK last season, and have just started using it again. Now, It will work OK when the skimmer just has a strainer basket, but when a hose is attached to the skimmer the pump won't prime (I assume that's the right term - it can't fill all the way, no flow). This happens even if just a short length of hose is attached to the skimmer. Without extra hose, the pump fills nicely, there aren't a lot of bubbles, maintains about 12 psi and seems perfectly fine. Could this be a leak, or should I just get a new pump? The only obvious leak now is on the output pipe where I did a temporary (2 years ago) repair. (I need to decide whether to replace the pump before repairing that.) Really need to be able to vacuum the pool!