I have a dollar says you have a deeply grooved basket not allowing proper disengagement , maybe engagement also. Also possibly out of adj. When you have it apart you can file the grooves on basket. Closely inspect the external shift mechinism for wear and adjustment.
NOW FOR MY RANT If you are to cheap to buy a Clymers, find a download manual. I'm tired of the age of entitlement where everyone wants everything handed to them. Understandably the search function isn't the best here but it does work OK. If nothing else scroll through threads manually. Follow threads, you'll already know what's wrong and how to fix it when it happens to you. These machines don't take a rocket sceicencetist (sp) to figure out, ain't nothing more than a big weed wacker.
If you have more money than sense, then be my guest and take it to my favorite, prefered mechanic. Ask for him by name at the service desk, his name is Ben Dover.
RANT OFF