One way you can tilt the odds in your favor- - - - -open up the "unknown" regulator before you install it, and give all three sets of points a good scrubbing with a piece of clean index card stock, or maybe a business card. DO NOT use a file or even a piece of fine sandpaper to burnish them- - - - -regulator points open and close with a slight wiping action which supposedly makes them "self-cleaning", and even microscopic scratches can make them stick. Good luck!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!