I removed the vernatherm on my 2000 70HP Johnson since the engine took forever to heat up to operating temperature. When I took out the vernatherm, there was a 9/32" ID O-ring on the diaphragm side. I did not see this on any of the manuals or the parts listing from my on-line supplier. The local shop knew nothing about Johnson. Was this something that some well-meaning mechanic decided to put in there that he should not have, or is there something missing in the manuals and parts list?