well, after a summer of frustration with the pool, i have thrown in the towel (yes, actually threw a towel right in the pool) and shut 'er down last week. i was advised here by my trusted pool gurus to check the gasket on the filters' multi-port valve because i was having problems with **** blowing back into the pool when i vacumed. well, i took the top off & looked at the gasket (kinda like a wagon wheel with a couple of spokes missing) and it didn't look bad to me. what should i be checking for? if it's a bad gasket how should it look as compared to a good gasket? i've had the pool for 4 years. thanx for your help in this matter.