My Gramps sent me this one for my birthday. It's a neat radio, and works well. However, the electrostatic tweeter is having problems. It sounds very quiet in comparison to the cone fullrange, and sometimes there is only a faint buzz. I think maybe the screens are shorting?

I'm not quite sure how to access the panel, as the front grille is non-removable, and the plastic back of the ES panel is stapled in. Also, if I try this maintenance while the radio is playing, will the panel bite me?

Furthermore, is this even the problem I think it is, and can I fix it at all? Thanks for your help.