casement operators, probably 30 years old

Looks like I can remove the operator only by first removing the wooden sill cap that covers it, and sliding the long arm all the way off the window to the outside end with the operator still attached. No problem physically, it's ground level. The guide channel is dadoed into the bottom of the sash and I don't see any screws to remove it. Have not removed the wood cap yet, would rather try to do this all in one quick operation. Not seeing any identifying info on the hardware and don't know who made the windows.

Tell me please what sort of info or measurements or photos you need to be able to hook me up with the right replacements. Right now I only need a pair, left and right.

Thanks,
John

It's a single arm operator, about 12 inches, with a Wright stamp on the arm, all metal. The short arm is non-removably attached to the bottom of the sash near the hinge, and fitted onto a stud in the sill. It's roughly 5 inches but doesn't need replacement. I've included a couple of other photos showing the channel in the bottom of the sash that the guide wheel of the operator arm slides into; there's no notch in the middle of the channel so the wheel has to be installed from the edge of the sash. And yes, so far all I need is the two operators although I've only disassembled one side.

Thanks for your help, looks like an exact replacement! Ordering today, will follow up after I install them.