This viewer is quite similar to
the one shown above on the side with the eyepieces, however, the
diffuser side has been completely remodelled. Instead of a plunger
advance mechanism this one utilised a thumbwheel. This thumbwheel drove
a rubber wheel which pulled the slide through the viewer.
A very common fault with
Colorscope viewers is that the body warps, resulting in the slot into
which the slide is placed closing up, to the point where it can no
longer accept a slide.
( Credit: John Mandjik for
the Instructions Sheet)