grundig: Best way to clean FM tuning capacitor

I'm currently restoring a Grundig Majestic 5088 USA and have the radio working on all bands and it sounds fantastic on FM. So far, so good.

Only problem is that when searching stations on FM the sound (whether it's noise or some FM station) will disappear and come back randomly when turning the tuning knob. Once I'm on a station I often have to wiggle (turn it back and forth a little) the tuning knob a bit to get sound and good reception.

Since the FM tuning capacitor sits on the outside of the FM unit I'm guessing this is caused by dust or other dirt in or on that capacitor.

I already used a vacuum cleaner and a soft brush to clean the thing as best as I could and while that helped a bit it didn't fix it completely.

My question is: what is the best and safest way to clean the FM tuning capacitor? Compressed air or spray it with Deoxit or WD-40 or.. ? What has worked for you?

Thank you in advance for your time.

Ton

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WD40 affects the capacitance. You need something that evaporates with no residue, like IPA. Paper the correct thickness with alcohol.

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Compressed air with low pressure can work but will not remove everything. Isoprophylic alcohol is also good to clean mechanical things.
I like to remove or at least disconnect variable capacitors and connect them to a powersupply at max voltage (450V in my case) and turn the capacitor. you will hear it crackle and see the dirt burn away.

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