[GreenKeys] Model 14 typing errors - lubrication problem? Misadjusted? Wrong selector magnet wiring?

[David Burns]

Jim..

Here's a bizarro investigative technique that might not be practical due 
to mechanical considerations, but I mention it in hopes of perhaps 
stimulating another more successful approach should this not work out...

The suggestion: Glue/attach a small (light in weight) piece of aluminum 
foil (bright-side up) to part of the armature on the selector magnet.  
Strap an LED and LDR ("light-dependent resistor") physically together 
("side-by-side") so that they both point in the same direction.

Now the easy part:  Arrange the LED/LDR combo to 'point' at the 
reflective foil on the armature.  By powering the LED and watching the 
output from the LDR (itself presumably powered by a small voltage 
source) on your digital scope, presumably (if enough light is reflected 
differentially back to the LDR depending on the position of the 
armature) you might be able to track the movement of the armature itself 
using the scope.  Alternatively, you might arrange the LED/LDR combo so 
that the LED points into the 'eye' of the LDR, and then arrange the two 
so that part of the armature mechanism occludes part of the path of the 
light between them on a mark or space condition.

If successful, you could address the hypothesis that the selector magnet 
isn't tracking the inbound data-stream correctly.

Or you could just rip the whole selector mechanism apart and clean it!  
("Good luck with that"!)

-Dave in Boston