If the spring in the check strap has been chewed up, then the ball can pop out.

You can't fix the checkstrap, just buy a new one. Just bolt one side in place, then put the other side in and it will work with no problem.

Do NOT try to pull the thing open before installing it to one side of the car or the other. I'd rather not say how I know this.

They seem to poop out from too much moisture and a lack of lube. The spring rusts and then comes apart or gets squooshed under the bearing, then the bearing pops out.

They can be lubed on the car with a spray can of lithium grease.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)