I have sand entering the pool at the return jets. i have a replacement 6 way valve because i cracked it when screwing the pressure gauge into it. the air strainer also appears to be leaking. my owners manual says that a damaged air strainer may cause sand to enter the pool. do you think this is possible or it most likely a broken lateral. also, everything was fine when we closed the pool. do you think this is due to a bad winterization or just normal wear? this is the 4th season for the pool. it was closed by a pool store.