I need more information to answer your problem. The chuck normally has movement turning because of the clutch gear. It is possible if you had a gear strip or spindle break that there are pieces of metal in the grease that have jammed your new gears. I would recommend tearing down completely, remove all the grease, thoroughly clean gearcase, regrease & reassemble.
Answers & Comments
I need more information to answer your problem.
The chuck normally has movement turning because of the clutch gear.
It is possible if you had a gear strip or spindle break that there are pieces of metal in the grease that have jammed your new gears. I would recommend tearing down completely, remove all the grease, thoroughly clean gearcase, regrease & reassemble.