Thank you for your help and advice.
Bill.
Thank you for the additional photos, Bill! I'm afraid we don't sell an operator cover that would fit the base shown here. Please allow me to consult one of our senior experts and we will reach back out as soon as we have more information.
Hey there. I can confirm that we don't sell any operator that matches the design exactly. That said it almost appears to be closer to the 39-315 in terms of size. The Encore style operators you mentioned before have a wider body and I don't believe they'll fit in the cutout at the bottom of your window frame. Something like 39-315 would be a better option in my opinion but look it over and see what you think.
Note that the cover comes built into the 39-315 and is not designed to be removed like your original. That does mean you can't swap that out for an alternative cover style. The only option for a folding handle would be our 39-205.