John,
Whether its a wingnut or Phillips I'd just forget about them both. The
quickest way I've found to remove the bar is to first disconnect the spring,
extract the bars pin from the side of the piano, and drop the bar down to
disengage the plastic nut. I then reverse the order to reinstall. I've never
had a problem using this method.
Good luck,
Paul Gates RPT
Farmington Ut.
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