David said 5/16 x 18 Paul said 1/4 x 20 I have to replace mine.... which is correct, please?? And is snugging them down with a bit of RTV on the gasket good enough?? -- Dave G. KK7SS '65 MK III Sprite in Richland, WA "Two things are infinite, the universe and human stupidity. But I'm not so sure about the universe." ... Albert Einstein.