Thanks so much, Paul. I'll push forward, then.
Speaking of A4/A5 (please let me know if I should post this separately), would a tight crimp on these terminals be responsible for the trouble I'm having inserting the 12AU7 in its socket? I managed to pass the glow test, but I had to really bear down on the tube and rock it back and forth a lot to get it fully seated. This is my first time with tubes, and I have no idea how much force they can withstand--or how tight a fit is ideal. Do things loosen up a bit with time? The 12AU7 did seem very slightly easier to insert the second time I attempted it.