I opened mine up and replaced gears (it didn’t fix my problem) I ended up having to open it up about 3 times. It’s a bit finicky inside and if you don’t put it back together right it’ll jam right away.
It’s not a difficult job. It’s a tedious job. It helps if you have long skinny arms.
I wouldn’t recommend doing the gears just for fun.
Adjust the parking brake first. Bodsy’s brake bible has good details on how