[Warren]

I found something strange. I found that when listening to AM and I use a wooden stick and brush it across the variable tuning capacitor plates I can either lose a station or it can bring more stations in. Do you think it is a bad ground, or the tuner needs cleaned better or maybe the plates aren't aligned right? They all look straight. Hoping someone can lead me in the right direction to fix this. Considering it can make the tuner pull in more stations , or lose the station, I am thinking this is my problem with not receiving a lot of AM stations. Any ideas?