No visible markings on crank or window and experts cannot identify manufacturer. The house was built in the 60's and we want to see if anyone can help us find this product.
Bob from SWISCO responded:
September 25, 2019
Thanks for writing in. Take a look at our 39-175 and 39-176 Pella Operators. Look these over and let me know if you think they're the operators you need.