Truth #41016/41011 operator identification

A handy person from Flagstaff, AZ says:
I have three operators that are stripped. The horizontal opening window is a Truth #41016. The two (2) right opening windows are Truth. #41011. Arms are a dark color- probably black.

What is the trick to removing the screws from the operators as they are under the sash area? Is there a special screwdriver for this?

Also, what is the difference between the 39-23b and the 39-239C units?

Let me know what you have available, cost and shipping dates.
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Emily from SWISCO responded:

Hello!

The 39-239B and 39-239C are the same operators. The 39-239C is just the stainless steel version.

As for the operator shown in your pictures, you could have either our 39-253LB & 39-253RB or 39-438B & 39-439B. These two parts look similar at first glance but the important detail to focus on is the design of the guide at the end of the arm. The video below will explain exactly what I mean.

It looks like your wood sill is blocking access to the screws which means you'll need to pry it off before you can remove the operator itself. I'll post a video below showing our preferred method. The operator in this video is different but you can ignore that part and just focus on the trim removal.  
Pricing for the items I mentioned can be found on their respective product pages and shipping will be calculated at checkout. 
Watch How To Repair A Casement Window Crank Operator
Watch How To Repair A Casement Window Crank Operator
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Comparing the 39-253LB & 39-438B Operators
Comparing the 39-253LB & 39-438B Operators
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Anatomy of a casement window
Anatomy of a casement window
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How to Orient a Dual-Arm Operator
How to Orient a Dual-Arm Operator
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How to identify casement and awning operators
How to identify casement and awning operators
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