There is a Gen He valve offered here for $68. Part #OME-086ST0115
Fits Planet Ocean and Bond case numbers 168.1649 168.1650, 168.1651, 168.1652, 168.1653
One of the model numbers that use this part is 2907.50.91
http://www.ofrei.com/page989.html
I'm not too sure if it will work but, I'm sure you can ask one of the more experienced mods for advice.
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)