[Arran]

Ron;
  I can't comment on this model specifically, however whenever I have encountered a radio with a burned plastic dial it was usually because someone used pilot bulbs with an envelope that was too long, or used one with a envelope that was too fat. This was a common problem with Canadian Rogers built radios of the mid 1930s, some had the bulb fit in through a rubber grommet on the back plate of the dial assembly, and at an angle, too long of a bulb and it touches (or nearly touches) the back of the dial and burns it, LEDs all around for those. 
Regards
Arran