I went ahead and tried to repair the contact patches almost successfully. The weird thing was that when I measure for continuity with a multimeter the black tracks, where the brushes glide, are not conductive at all. Couldn't measure any resistance either. The only conductive part are the circular patches. There is no continuity between the first and third patch either?! I am a bit confused as I thought this is a potentiometer and I was expecting the tracks to be conductive?
Anyway the patches were giving bad contact so I applied some silver conducting paint. This things flows and dries very weird and I wish I tried some elsewhere first.
I also applied some to the ends of the springs, where they contact the patches. Everything measured OK.
When I put it back on the cruiser it didn't work and the OFF light was blinking

Techstream showed
C1713 - Rear Height Control Sensor Circuit. Rear height reading was stuck at 181.2mm and the sensor went from giving random readings to being stuck
This puts the AHC in safe mode where it adjust by pressure - aims for 6.5MPa front & rear. With Kings springs this puts the rear slightly higher than normal. At least it's drivable that way.
I went for a few rides for about 200km this way and at one point the AHC
just started working??? Techstream shows normal rear height values and pressures, truck moves L-N-H.
At this point I haven't yet done the FSM test with applying 4.5V and measuring voltage across the sensor range. I guess the sensor made good contact again, but who knows for how long

. I am going to drive like that until the new sensor arrives