I used the term thermocouple since most people know what this is. This probe is often called a capillary tube. The correct term for a device such as this tube is a manometer.

But how many people know what a manometer is?

And while it is true that many modern expansion valves are connected to the manometer this one is not. Mercedes chose to cycle the compressor as a means of regulating the A/C output temp. Modern expansion valves use the opening and closing of a valve, which is piloted by the manometer, to control the rate of expansion of the gas, using high and low pressure switches in the system to cycle the compressor.

And this device has a bourdon tube but it is inside the round body of the item and is not repairable.

The only realistic solution is to hit Ebay and pick up a working replacement. If this were a 300sl Gullwing the tube would be repaired as gauges and switches like this one are not readily available.

And there is also the solution to just install a switch to cycle your A/C compressor. You will likely freeze up your coils by doing this but they will melt off in a few minutes of the compressor being turned off.