Hi SGP,
The linkages between the auto gear levers as well as the manual levers have nylon bushes which don’t last for ever. Eventually they start breaking up, disintegrate and fall apart and you have what you describe.
Apart from being a nuisance not being able to select the correct gear, or driving the car, it is not a big deal.
These nylon grommets are available and once replaced, your SL will feel like a brand new car.
Regards
Chris