[morzh]

So, some removal and some cleaning.

Taking the parts out, obviously, take some desoldering.
I use the bamboo skewers from grocery shop to separate the wires upon melting the solder.
Like so:

   
They then come apart easy and don't re-solder by themselvs.
   

This is the potentiometer: this one could use some contact cleaner used judiciously.
   
   

Then I opened the variable caps and re-insulated the wires. The insides otherwise are very clean.
I also made sure the spring contact makes contact with the case, which it did very well.
   

Then heatshrinking the wires:
   

And I used rubber grommets with rounded edges to make the tires for fine adjustment knobs.
   

When a better one becomes available, I will put them in. It is easy.