@jwmorris
The WX2 I lent you was from a Vandy 2w sub from about 20 years ago (serial # 4K).
So, if you found it stable, then something went wonky with the one you have. Perhaps Johnny or Mr. V. could provide some info?
I was going to call Johnny R and get his feelings on upgrading/checking my subs. I just got a pair of 2WQ's (about 4 yrs old), and can tell that there is a difference between the 2W and 2WQ. Whether it is due to the 'Q' or that the 2W's are so long in the tooth, I don't know, but I think taking them to Johnny for an overhaul couldn't hurt. I'll post what I find out.
I recall Mr. V telling me that if they make a 'thump' when you plug them in, then they are working.
Bob