1980 Princeton Reverb Vibrato Always On? HELP!

[weverette1]

80 PR, Pull Boost version.
Pull boost disconnected, and using pull boost switch to connect the vibrato circuit and turn it off or on without pedal.

BUT, when the pull switch is in on position(out), the vibrato cuts off. That's backwards! It's as if the vibrato is always on, until you connect something to turn it off. That don't sound right.

I've done this same mod to a 81 VR and a 81 DR, and when you pull the pot out the vibrato comes on.

Any ideas? Theorys?
Guesses?

[Don Moose]

That's how the non-pull-boosts work, too. To get the trem to turn off, you gotta hook up the footswitch or a shorting plug.

Grounding that spot in the circuit stops the trem oscillator.