Need replacement parts for Marvin Casement windws

A quick learner says:
Hello, I have broken crank assemblies for 3 Marvin Casements. The part numbers on the Truth Entryguard operators are # 30842R and # 30841L. I also have a rusted lower arm # 30744. To replace the lower arm, I think I need to purchase part # 36-013-10 (for 10 inch). Can I order just the lower hinge assembly or do I need to buy a pair (of upper and lower)? Can you tell me what parts to order for this homeowner project? Thanks.
User submitted photos of a window operator.
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Paul from SWISCO responded:
It looks like the worm gear has come out of your operator, based on your first picture. This cannot be repaired, I'm afraid, so you will need an entirely new operator. See our 39-031 and 39-032. The bottom arm you mention is the hinge. The 36-013-10 could be a good match, but I would just confirm the measurements are correct. Same goes for our 39-031 and 39-032. We always recommend double checking your measurements.
A quick learner from New Hampshire says:
Thanks Paul. I took a final measurement and the fit of the recommended operator parts looks right. One final question regarding the pair of hinges....I only need the bottom (to replace a rusty component). It looks like I am required to buy a pair of top and bottom. Is that true? If I use one on the bottom, can I save the second for use on the bottom for a window that swings in the opposite direction? Thanks for your advice.
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Paul from SWISCO responded:
My pleasure! I'm glad my suggestions are a match.

Yes, the 36-013-10 is sold in pairs. You could save the second hinge for another window, but we actually think it's a good idea to replace both hinges on one window at the same time. While I believe that the 36-013-10 is compatible with your current hinge, there may be some subtle differences that will make the window operation a little uneven.

That said, there may be no subtle differences at all! You could always play around with it and see if it's something you can get away with.
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