big muff pi ( 70s) please help with unsoldered bat connector

[sidewinder]

hi , i have a big muff pi from the 70s and i was messing around with it when the black (negative) batteyr connector got unsoldered from the board. can anyone show me wher ei have to resolder it???
much appreciation to those who answer



red = where the positive wire is soldered

[petemoore]

I'd hunt down a known ground point, like the volume or gain pot's CCW lug, I think the cases are grounded on BMP's so that would be bat neg on an NPN version, or pick a transistors emitter resistor, follow to the other side and that would be ground.
 I think the battery - connects to the ring of the  input jack though.

[sidewinder]

thanks petermoore i di dmanage to get it working finally