My little input- I'm a mb tech. at a dealer, & we're sometimes able to 'pop' the ball out of the Lambda tower by tapping two hammers on either side if the tower at the same time, being careful to have a rag covering the air intake valve...(ball bearing in intake = not good .

Before adjusting the Lambda setting, make SURE you know what you're doing & why. This adjustment is very precise & not very forgiving.