Very early 230 SLs have a gas float with a float on a lever that could bob up and down the sloshing of fuel. Based on what cars you have listed, it is unlikely that you have this type of float. All other Pagodas have a tube type float with a plastic float that goes up and down on a wire based on the level of fuel within the tube. The design of the tube type float is such that only a very restricted path exists for fuel to go into and out of the float - the result of that is that sloshing in the tank has no effect on the float itself because it doesn't respond quickly to changes in gas level. So it isn't the result of sloshing fuel.
When I have salvaged, cleaned, and sold floats (which I do on ebay, forums, etc) the typical problem is that the float contacts are dirty or there is corrosion such that contact is intermittant as the float travels. In your case(s), it sounds very much like the wires or contacts on the plastic float are not making consistent contact. This could be because one of the contacts has slipped off one of the wires or more likely, because something is grubby on the lower portion of the float wires/contacts. Or that there is contamination inside the float tube, which settles closer to the bottom and only interferes with contact when the float is in the lower range.
Your remedy is to try to clean the float or to replace it.
