Litton:

Your limited slip sounds like it is working properly. The internal clutches of the differential are designed to provide a locking of the two axles via the clutches, or cones depending on the design. These clutches join the axles so that in a straight line the two wheels will lay down those two long patches of rubber. Without the LS, the unloaded wheel, usually the right one, will lift slightly, break traction and then all the power transfers through the differential spider gears.

When you make a turn there is a need for the inside wheel to turn at a different (slower) rate than the outside wheel on the turn. The differential spider gear set allows this to occur. When you have a limited slip, (other names are positraction, traction lock, sure-grip, etc.) the internal clutches are designed to "slip" and release their lock on the two axles so that the necessary speed differential (note the terminology, that is why the rear gear set is called a differential) between the wheels can be achieved. There is usually a break-away torque value designed into each LS differential. If you raise the rear off the ground, a normal open gear set allows one rear tire to rotate in the opposite direction than the other (spider gears again). With LS, they rotate together (locked up by the LS clutches) but, if you restrain one wheel a bit (like when you make a turn) it will break the clutch locking action at that pre-determined torque so that the two wheels can achieve the the required differential speed.

I'm sure there is some complex MBZ test method for determineing whether your unit is operating properly IAW MBZs specifications. But here is the fast, simple and more fun way. Set up on a clean straight dry road. Make sure your tires are equally inflated. Check for cops, if all clear hammer the gas and peel out like hell. Go back and measure those black marks. They should be equal length, more or less. If so, fugedaboutit. Diff's fine. If not, check your bank balance and if you're flush, get a new diff if you fell like you just gotta have LS. Unless it's making noise, an ineffective LS will not cause you any problems, it just won't give you the benefits of LS if you need them (think snow).

For what it's worth,

230/8 (former street racer, but reformed for many years)