Casement operator on vinyl window. No apparent markings on arms or handles

Hello, thank you for posting,

Please start by reviewing the style and dimensions of the 39-329 and 39-330 ROTO operators along with the 39-232 handle. Compare to your originals to confirm a good fit! 

I am hesitant we can assist with the locking handle. Are you able to show us the lock removed or the other side where we can view the engagement point? Thank you!