Dale, I had the same problem with the same air valve. It was hard to see the hairline crack. The leak was strong enough to blow my soapy water away, but I found it with an Xacto knife, put cuts in the plastic for the JB Weld to grab onto and liberally spread the JB on. 'Worked for me. The leak stopped completely. The seat rarely needs adjusting now. I figure I've paid for a lifetime supply of JB Weld in the savings on just one job.

My photos showed only a glob of JB Weld.

Ron