the Edsoto videos should reveal this, or at least, show the
disassembly which accesses behind the rotary switch.
http://edsoto.com/E320.iso
this is a 500mb file. download. then save/burn to CD. it should contain
dozens of disassembly videos for the 210, especially for the instrument
panel
the host server is finicky but give this a try....
http://edsoto.com/e320/w210/disassembly_interior.htm
it will show various portions of the 210 in how-to-disassemble stages