Do you know what make and model window you have? I'm not aware if you can 'fix' these cranks. I have Pella crank windows, and a few years ago, I had to buy new ones.
In your case, check with the mfgr.. Also, if you know the 'cause' of the damage, do look into mitigating that. If it's simply stripped due to 'normal use', well, that would be normal.
My best to ya and hope this helps.
Jay J -Moderator
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