On Sun, 29 Jan 2017 17:53:42 -0600, Dean Hoffman
wrote:

There is something called valve stem packing. No idea if it would help:

https://www.bing.com/images/search?q=valve+packing&view=detailv2&&id=04E4BA1AE B8329FCEBAB2AD567791B14FE88FDAA&selectedIndex=91&c cid=B7xLDEz2&simid=607999669158677037&thid=OIP.M07 bc4b0c4cf6d1387ce946dfe529af48o0&ajaxhist=0

Home Depot or Ace Hardware should have it. It looks like string.

Commonly called packing "rope".