Allan,
I’m glad the first issue was so easy to fix.
If the tonality of the pedal is changing over time the only thing i can think of is that it might be a solder joint issue. As in, the signal is being hindered by some bad connection somewhere…and somehow it’s getting worse over time. You can always try to wiggle components with your finger as you play through the pedal to see if you notice the tone changing.
It’s a weird problem that i haven’t seen before. I hate to ask this, but are you sure it’s not your perception or ear fatigue? To test this, you could try to record a riff on your phone when the tone is set the way you like, and then record the same riff again after you play through the pedal for a few hours. That would give you more of an objective opinion about what’s happening.
That’s all i know to say about this issue at this point in time. Let me know if you try re-soldering things or try the recording test.
Good luck.
-Brach