The motor on the left does not look like an original Gottlieb installed score motor. The one on the right looks more like an original motor. Install it and give it a try. It can't hurt.

that is not a oem gottlieb motor, not one that I have ever seen. use your spare it would be an
Improvement even if the other one worked fine.
my guess it was replaced at one point in time
the only real difference in early 60's and mid 60's score motors is that the later style had the ability to pivot and move off of the bracket. earlier style you had to un screw it from the motor board
but both styles looked almost the same nothing like the one shown.

As long as the output shaft of the spare motor is the same as the hole in the hub on the cam use the spare. I believe the output shaft on earlier Gottlieb score motors, aka wood rail era, were smaller.