[keith49vj3]

OK guys, I need some advice.  I've never worked on a car radio  is this old.  My first question has to do with this interference filter that I've got shown in the schematic boxed in red and in the attached photo.  It appears to be a coil and 250pf capacitor that I believe is potted in Tar.  I'm not sure if I need to mess with this one or not.  Can I melt off the tar and then replace the cap?  The next question involves the buffer capacitor.  It's a 1250pf capacitor, can I replace it with a 1000pf ceramic cap?  I've ordered a new solid state vibrator for this radio.  My last question regards the polarity of the electrolytic caps.  I've never worked on anything that was positive ground so I need to make sure I've got this right.  Is the negative side of the electrolytics attached to the ground?
Thanks in advance,
Keith