[morzh]

I washed my cap in dish soap and then dried it just shaking the water off and leaving it on a paper towel for as long as I did not need it, but it will be dry the next day for sure.
I am not sure what the film inside those trimmer caps made of, looked like it got soggy after the wash, but it dried up and seems t be OK.

Those two spring contacts rubbing against the shaft are grounds, and there are two of them, so should provide good connection.
The screws for the stator - keep them screwed tightly when washing the cap, then after wiping/shaking water off, unscrew and let dry, so whatever got inside will evaporate.

I simply wiped the dial with alcohol.

Microphonics: get into where it is pronounced and using a insulating rod with something soft at the end, keep touching and lightly pressing at any suspected elements. Tubes, tuning cap's vanes (very lightly though they are fairly thick to be bent easily), even coils.

Also, apply some twisting effort to the coils' shielding cans to re-establish the Ground connection - often times they are floating due to oxide build-up. Twisting even if the can does not move breaks the oxide and reestablish connection.
You can easily check that with moving your finger closer to the 1st RF can - the volume of the current playing station goes way up (did do that in both 70 and 90 in my case) and touching it simply tries to rip the cone of the speaker. After twisting that should disappear. (well you did that already..still).

What else.....


PS. Have you check all voltages? Especially those coming off of that big multi-tap resistor?
Check all voltages at the 2nd detector.
PPS. The last thing is - the radio could be BADLY out of alignment. This will screw the sensitivity.
Once done with assembly, try to align. See if it comes back.