An additional lock engages at the tips of the arms. Loosen fastener 5 - 6 turns to provide clearance for FRT under washer. Capture the fasteners by positioning FRT tips underneath washer and engage the lock by pushing on the Delrin knob. Loosen fastener fully for removal. Fasteners are released from FRT by pulling back on the Delrin knob.
Washers have rubber ring on inner diameter providing a semi-captive feature to screw shank.