Servo motor sizing & source

To the group;

I need to replace one of my servo motors and wanted to figure out the 'size' of the existing motors [to assist is buying a replacement]

Looking on line, the motors are sized in in/oz values yet my current motors do not list that value.
Is there some way I can calculate an in/oz value based on volts, watts listed on the motor?

Failing that, what is the recommended size of servo motor I'd need using a 2:1 drive ratio? This would be used to drive my ball screw Z axis on a m/d conversion.

Thank you for your time.
regards

Owen Lloyd
CMRA #111p
"Never trade the thrills of living for the security of existence."

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