Reading back through the thread just now, I realized that I never replied to your helpful post. So sorry! Just because I'm retired, doesn't mean I don't get interrupted occasionally. I haven't made any progress other than replying to posters today due to an overnight visit from my not-quite 3-year-old granddaughter. She's a wonderful distraction! The scope can wait when she's around.
I just ordered a powered desoldering gun after some frustration with my spring-loaded one. I had never used either before, so didn't know what I could achieve with the spring. It didn't seem too bad, and probably will work fine on a single-sided board, or perhaps with this board for certain components, but the big caps and their associated ground lugs present more of a challenge. After watching the powered ones being demonstrated on YouTube, I don't think I'll regret the purchase. I have used rosin core solder quite often in the past, but never had flux on its own except in plumbing, and one doesn't get far with solder wick without flux. If the desoldering gun won't do the trick, the flux and wick will have to.
As far as heat goes, my impression is that quite a bit over a short duration is preferred over too little heat over a longer duration or too much heat, period. Also, the Weller with stock tips is much cooler than the #14 copper wire, if Mr. Carlson's example is instructive. I've only used the Weller in soldering since I got it as a gift back in my 20's until I got the Yihua recently. I did get a cheap 20W for a more delicate project that I never used again. In retrospect, I probably wasn't using it properly. When I do copper plumbing, I use propane or MAP, but that's a different kettle of fish. So, I'm going to try to use the Yihua and resort to the Weller if I need more heat. It does take more when there's more thermal mass to heat up, as seems to be the case with the lugs associated with the PS caps. The flux should arrive tomorrow.
You and one other have suggested the round PCB's. Thanks for the Ebay listing! I'm going to take a look at my options after getting the caps out and being able to see what I'm dealing with. Probably will go that route, though. Also like your idea of reinforcing the through-holes with brass ferrules. Do you flare the ends, or just solder some appropriate diameter brass tubing in there?