I am new to the forum and I experience a similar problem of noise on the Black Finger.
My unit is 8 years old and a few years ago it started to have a random noise when engaged. It is a kind of hum (probably some coloured 50Hz) that appears and disappears. It stops when the the compressor is disengaged and re-engaged with the switch but comes back after a while. Typically it starts a few minutes after power up and also it follows notes or heavy playing for several seconds and disappears.
I changed the tubes, 2 at the same time and one by one. When I saw this post, I resoldered all the solders on the PCB, tried to re-screw all the screws but the problem is still there and the unit is not usable …
The interesting thing is that the noise is present in all the modes (lamp, led, sqsh and norm whatever the combination) even with the pregain at 0. The amplitude of the noise depends of course of the post gain.
I use it with an active MusicMan bass and the noise is there whatever setup I use (other pedals before or after the unit in the chain, BF alone …)
Do you have any idea of what component could cause the noise ? You seems to point out the power supply section. I could try to change some stuff inside …
Thanks for your help,
Nicolas