Sorry we missed your first post!
I was going to say that this sounds like a bias problem, and ask if you had adjusted the internal trimpot at all. But your follow-up about power is interesting. You will find a lot of hate for the 1Spot and associated products on this forum.
As I always say, they work fine for me (both single power supplies and my CS7), but I can't deny that we see tons of problems with people using them. Have you tried one of the normal 9v outputs on your power supply? If that works, then we've narrowed down the problem to the power step-down. If not, then it's probably connected to whatever is inside those Truetone PSes, and the answer will be to power your Leeds Fuzz a different way.
FWIW, the draw on these pedals is quite low, so a 9v should last a good long time as long as you disconnect the input cable when you're not using it. (Or a related trick would be to keep the input cable in place, but plug in the power supply until you're ready to use it. Either option will physically disconnect the battery and keep it from dying when not in use.)