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you've got an asymmetry somewhere

the pins may not be identical

the crank arms may not be a match

when the difference is in the pins then the usual procedure is to file the cut on the pin with the lighter cut

another thing you can check when the pins are in this state is the opposition of the crank arms -
they may not be a symmetric one hundred eighty degrees...

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here is one that will sound silly at first -

sometimes if a wedgebolt has worked loose in the past the combination of play and the torque of pedaling can gall up the walls of the wedgebolt hole in the head of the arm

rare, but takes only a moment to check for this


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