It's stihl a crap design, doesn't matter how you look at it. Doesn't matter how much you clean around the caps you're gonna get crap in around the oring and the boring will eventually give up the ghost. The simple solution would have been to go back to the treaded caps of a slightly different design then the original ones. Husqy sure had the right idea and stihl took a left turn, ran past the road closed sign and off the bridge.