Update
Updating database... Please wait.
Sunday 1 April 2018 at 21:17
Q71 would be the left slingshot. Q75 is the left popper.
Does the left slingshot work?
I would run the tests again. Some of those transistor cases look a little corroded so scratch a little bit with your probe to make sure you've got a good reading.
Source: http://pinside.com/pinball/forum/topic/taxi-popbumper-stuck-in-on#post-4314405