Broken Window operators

We should definitely be able to help. You have either a 39-253LB or 39-438B, depending on the guide at the end of the arm. See the video below to understand what I mean. That should allow you to pick out the right match.

It sounds like you already picked it out. That would be the 39-253LB. If you also needed a handle and cover, see the 39-451. 

If you wanted the opposite side, that would be the 39-253RB operator and the 39-452 handle/cover.

There is a right and a left, but it's not determined by the direction the window opens. It's determined from the outside looking in. I can tell you that the operator in your first batch of photos is the 39-253LB. If you need the opposite side, that would be the 39-253RB instead.

Sure, replacing these operators is very easy. You simply disconnect the two arms from the sash, unscrew the base from the sill, and pull it out of the window. Reverse the process to install the new operator.

Let me know if you run into any issues, I'd be happy to help.