The four pictures show the pivot bar which inserts into the housing shown. The housing sits in the frame of the window and the bar fits into it on one end and the plastic shoe on the other end which is attached to the balance. It is the little bar which I am missing. To me it looks like
26-089 except mine has only two drilled holes rather than three. But one of the drilled holes is in the correct spot at 2 1/8". Does this seem like the correct choice to you?