Marshall Valvestate 8080 FX Loop noises and "dirty" clean channel

[d3vCr0w]

Hi people, hope you're all doing great, I have a Marshall Valvestate 8080 which is behaving weird, the clean channel (with the switch set to clean) sometimes sounds dirty, as if it was the overdrive channel but with low-mid gain, if I strum hard it definitely sounds crunchy (something that is not supposed to happen, as sometimes it sounds really clean, so definitely something is going on), and tonight I was trying a distortion pedal and noticed that there's a noise coming out of the speaker whenever I toggle the Db switch from the effects loop, here's a video showing what I tried to explain:

Is that a common issue? Any help is appreciated, thanks beforehand.

 

[Tatzmann]

Hi guy,

all the switches in the front
need to be cleaned thoroughly
with electronic contact cleaner.

If your in there all the pots need
to be cleaned VERY good.

The Valvestates and the JCM900
have the worst potentiometers of
all Marshalls in terms of crackling.

You have to clean those nearly all
year because the crackle returns.

Speaking of return...all the Jacks and
their corresponding jackswitches need to
be cleaned thoroughly.