[Arran]

 Just for the record, this set takes a 6Q7 not a 6R7, electrically they are somewhat different but even so that should not be causing a motorboating problem as the pinout is the same.
  Just a thought, but is the pushbutton for dial tuning pressed in? Unlike most sets it's pushbutton number six rather then pushbutton number one. Are all of the tubes in the correct sockets? Are any of the tubes not of the type specified on the schematic? The eye tube and the motorboating issue are unrelated, as Mike said you can pull the 6U5 out and the set will work fine.
   If it is not one of these basic things then it may be something like a poor solder joint, or one end of a capacitor is connected to the wrong terminal. C19 and C21 are two capacitors that should be checked.
Regards
Arran