Need replacement

Hey there!

Thanks for reaching out to us. We don't sell an operator with a 12" arm. The 39-013 and 39-014 would be our closest options. The arm is 13-1/2" long when measured from the center of the gear to the center of the roller. Measure as shown below and see if they match what you're searching for. 

Dimensions for 39-013

Dimensions for 39-014