I have acquired an old (antique?!) GE single phase AC motor to power one of my (equally antique!) machine tools.

I’d like to make it reversible, through the addition of a direction switch & fortunately, the directions covering how to do this is printed on a sticker inside the motor’s wiring box cover. All well & good.

The problem is with these directions and the associated wire colours on the motor don’t jive.

The instructions dictate that I should swap the connection posts of the ‘Red’ & ‘Black’ wires. All very straight forward, except that there is no ‘Black’ wire on the motor. Instead, there are 2 blue wires – one pale blue & the other a darker blue-grey, but far from black.

My guess is that the blue-grey wire ‘should’ be black and that this is the wire I should be swapping with the red wire to control the direction of rotation?

Can I try this assumption without risking damaging the motor?  OR how can I conclusively verify which of the blue wires is actually the Black one?

Much appreciated!