I recently purchased a new 14t 48p pinion gear. When I screw in the pinion gear to my motor shaft the screw doesn't go in all the way but it is really tight and won't fall off the shaft. Is this okay or does anybody know what I can do to make it go in all the way

It should be fine, the set screw typically doesn't go all the way into the pinion when it's on the motor's output shaft, just make sure it's on the shaft's flat spot & tightened down good, & it should be just fine....

Thanks for the help, much appreciated.