Which gear are you talking about having slop on the ZA motor?
If you are talking about the gear that the pucks are inside then 10-20 degreese of movment is not bad. They are all custome fit to 2 gears I have at home. I massage there size till they fit snugly into both gear sets.
There is sometimes a bit of discremency in the size of the openings in the gears so some may have more slop than others.
If there is a lot of movment then let me or 1977 know.