From a wah-wah pedal only 2 years old so I don't see the point of replacing
with more of the same, as these symptoms are very common.
Poor bypass function and now total failure to switch between on and off
Both 1.8mm x (11 down to 10mm swaged )stainless steel rivets ground off to
separate the halves
http://home.graffiti.net/diverse:graffiti.net/ppsw.jpg
Unless anyone knows differently then I suspect the poor bypass contact is
due to the interior packed with non-conductive grease.
Carling, Mexico is the make of this one , single pole c/o, silver plated
contacts and dumb-bell that can just about be seen in the centre of the top
image,then a locating cup, then compression spring, then brass cup that
seats the end of the swinging arm marked L in the next images. The dumbbell
jumps the 2 contacts at the top of the image and runs along the continuous
lower one.
(not sufficient control over exposure on a basic camnera)
Cleaned the silicone grease out and will replace with heavily graphited
silicone grease,as not used for mains switching here, otherwise 1A 250V / 3A
125V rating. Why silver plating and then non-conductive grease in low
current/ low voltage use ?
There must be a "ball point pen" type latch action in the bush part so the
down action pushes the L arm one way then the other on the next down stroke,
with a click of its action on each upstroke.
Presumably due to wear the underside of the button eventually bottoms
against the end of the threaded part marked V, when L is only half way
across. It needs to go a bit further than half for L to swing across, via
the dumbell/cup spring sub-component action , to the other side.
Slightly tightened a small Jubilee clip around the threaded bush, as a
guide, and hacksawed off about 2mm at the V position, not apparent in these
images, so can be quite neat.

No matter, in this case (not mains use), as will replace the rivets with
Spanish windlass "E string" wire over 2 pins and glued in place. Anyone know
of a source of such small diameter /long rivets for other occassions?

Of course just fixing the lack of switching does not require removing the
rivets

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/