Zenith transoceanic H500

[radio nut]

Hello, i recently bought one of these sets from Ebay in restored condition. It worked pretty well, and the I bought the reproduction battery pack and loaded it with batteries and tried it out...At first it really performed much better I believe because there is no interference in the power cord. But it started going quiet until the tuning capacitor is tapped lightly. I did use liquid deoxit on the tube pins and antennae connection. I even tried deoxit in the tuning cap wipers...then QD electronics spray cleaner. I did see a little black stuff by the wipers and tried a qtip with alcohol on it..i did get some black stuff off but now all i get is maybe 2 local stations and loud static when i try to tune other stations....ok now what do I do?