Started to balance Jenvey pairs at idle. Number 5 was reading 3 times more flow than all the others including its brother number 6. I see that the butterfly has some play relative to its brother which explains the symptom. I tried to remove screws holding the Jenvey nameplate on but couldn't budge them. I don't want to be brutal with them unless they have to be removed to access a spindle connection. So is there a join between the two butterfly spindles or are they one. It doesn't look like the butterfly is loose in the spindle. What Next?