Well, I decided to re-stuff my doorknob cap. I ordered 10 ea 470pf 20Kv caps from eBay for $6 shipped.
http://www.ebay.com/itm/282085716087...%3AMEBIDX%3AIT
I cut off the bottom end right at the bottom portion of the main body. See the red arrow. I used my trusty band saw and took my time. No room for error.
Here is a picture after the bottom is cut off.
I then used my Dremel with a Robart 3/8 ball carbide cutter
http://robart.com/collections/hobby-...-8-ball-coarse
to grind out a cavity to house the new cap. I kept at least a 3/16 edge so there will be room for the epoxy to glue to when gluing on the bottom. I ground down till I can see the copper end post.
I then used some flux and solder to coat each end till my caps arrive.
More to follow when the caps get here.