MOTM

As Paul mentioned in his update, these are larger than the Switchcraft 
washers used on other MOTM modules.  The jacks are larger in diameter, 
too, and take a different nut size.  A slightly smaller washer, ideally 
the same outer diameter as the regular washers with an inner diameter 
big enough to fit the jacks, would improve the appearance of the 650.  
The washer sizes are:

Switchcraft:  O.D. 5/8 inch (about 16mm), I.D. 3/8 inch (about 9.5 mm)
650 washer:  O.D. 18mm, I.D. 12 mm

The ideal washer would be O.D. 16 mm and I.D. 10 - 12 mm (12 is larger 
than necessary).  I am not sure what's the minimum to fit the jack, but 
it's larger than 3/8 inch.  Paul, what hole size is drilled for these 
jacks?   If anyone finds such a washer obtainable in the U.S. in 100 
quantity I would be interested.  (I imagine that Paul applied due 
diligence here, but who knows what we all might find.)

Richard Brewster
http://www.pugix.com