hi there one and all, i have a concern regarding noise that i've recently come to hear whenever either of the two toilets in my home is flushed. i can hear gurgling, and the sound of flowing water.someone suggested that there was a gas/air problem; something to do with a valve? i'm not terribly handy, yet can't afford a plumber, at present. is this something that a novice can accomplish with the proper direction? thanks for any response(s). cmb