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So I have been using the PVAK on my 1291 for about 7 months now and it works perfectly. However, the o-rings on the second valve seem to be stiffer/harder than the other ones installed. This causes the second valve to make a nice thud sound whenever in use. In wind band people don't exactly care, but in exposed situations I get more than enough negative comments about the valve clutter.

It is odd, because the other three pistons are very quiet and work the way I want them too, except for this second valve. I didn't install it wrong or anything, and my personal diagnosis has lead to this assumption. What would be your thoughts on this? Maybe just switch them out for the stock synthetic felt things that came stock with the horn for the second valve, or switch out these "dud" o-rings with a valve that doesn't see as much action? A sense of direction with this would be much appreciated!

If you are happy with the PVAK overall just replace the o-rings with new.

Rubber does go hard and brittle over time and the second valve gets more use.

Most larger cities have a rubber company that sells o-rings. Find yours and bring in what's on the horn to match. They'll sell you a lifetime supply for a dollar.

It's possible that the top valve cap on your 2nd valve is not seating properly. Try loosening it off just a fraction of a turn and see if the noise changes, then try tightening it. You may need to clean the threads at the top of the casing and inside the valve cap.

Thank you guys!