air leak

Hi,
When I opened this spring, I realized that air is getting into my system. What would happen is that the basket (just before the filter) would slowly fill up with water, then the water level would suddenly drop, then fill again. After tightening all my connections, and changing several seals, I tried by-passing the line from the pool (i.e. from the skimmer basket) by running a line directly from the pool to the filter. Voila, no more problems. So.... this leads me to believe that I have a break between the pre filter basket and the skimmer. (I think this line runs underground.) Is there anyway I (not a pool expert) can do anything with this leak. I've called the pros, but they seem busy, so I thought I might ask you guys.
Thanks,
..... john