Hello how are you
It sounds as though you have a stripped or broken gear or gears in the box. The only way to know for sure exactly what you need it to disassemble it and inspect the components. This usually happens when the incorrect shear bolts.
Here is a link to a couple videos on the repair process, after viewing the you can decide if this is a repair you want to tackle on your own or with the assistance of a repair shop.
There are 4 video in the process
Geez, Sorry videos
If you have further questions or problems let me know. You should find a link back to this question in your email. Please remember to click on the accept button, it is the only way i am compensated for my time...Thanks