The broken piece (pictures are of the broken piece attached) says Spect US. It is part of a Wellington Tilt Window installed in 1998 (Wellington is in MN).The half circle area is where the peg broke. A screw goes in that area to attach it to the window. The other part of the peg is still attached to the window frame.
The full peg has two holes and broke when I was tilting the window out to clean it.
Casey from SWISCO responded:
September 7, 2017
Thanks so much for your question. Please take a look at our 26-357 pivot bar and compare its measurements to yours. Let us know if that will work for you.