It's not a lifter or a follower, because it is stationary in the head. "Ball stud" and "compensating element" are synonymous.

I personally would replace the element in question before starting the car. There is a chance that if you start it as is, the element will pressurize and be OK, but there's also a chance that it will not and that it will damage the cam.

And yes, if they are bad enough, they can sound like the engine is coming apart.

Several posts on how to replace/adjust the ball stud.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe