Casement window operator need part

I am very confident that we can supply a match for this balance. Before I recommend anything, can you detach the arm from the track and show me the black slider at the end of it? That will allow us to determine the best part for the job.

It's very likely that your cover can't come off. Many older operators in this style had covers built into the operator itself. 

We don't need you to remove the cover, though, we need you to detach the arm from the track so that we can see the slider it uses. That will determine the best replacement.

Thank you! That's exactly what we needed to see. I recommend our 39-253RB operator. This newer style actually does have a detachable cover, which is sold separately, see our 39-452.

Sure, those would be the 39-253LB operator and 39-451 cover/handle.