Yeah, I installed a brand new seal in the cap that Randy (Wolffarmer) graciously sent me.
On the first assembly I didn't use any sealant at the valve to font half coupling, and I am pretty sure it leaked there initially. So I took it back apart and used Teflon tape. That seemed to fix it, but now I'm not so sure. I also had a leak at the valve stem, but that seemed to go away by tightening the gland nut some (I had lost a little chunk of the graphite during the rebuild, but was hopeful that there would still be enough compression to squeeze it back down... seemed to be okay before).
So it sounds like I have a leak and just need to find out where it is coming from(?).