Can definitely understand the desire to obtain more of those insulators. Generally, I get old heads from friends who aren't into rebuilding them. I've been able to keep my stash "fresh" with this method. Problem is, quite a few of 'em are moving on to RBAs, so the trickle of spare parts is dwindling fast. May have to break down and buy new heads. Some of the "chimneys" are getting quite loose as well. (Yeah, I've been rebuilding some of them for a while.)