Mellotronists

Hello,

I am going to take a look at a Mellotron M-400, tomorrow
afternoon.  Since I've never played, or even touched a
Mellotron before - I don't have a baseline to determine the
quality of the instrument.

Are there some very simple things to look for on the
instrument?  The seller has (2) additional tape racks for
sale as well.

Any recommendations are appreciated.

Thanks,

John Hofmeyer