Thanks for the additional information. I found another collapsed ball stud after I made the post. I did in fact stop by my local full service auto supply store this afternoon and looked at the KD3087 spring compressor. It seems to be the same design as the MB tool. I have also been in contact with someone concerning the rental of the tool.
Further "investigations" have revealed what seems to be some binding as the cam lobe passes over some rocker arms that don't seem to be able to be slightly compressed like the others. I am thinking that these may be in fact seized. I need to get the spring compressor and remove the rocker arms one at a time to isolate the one making the noise associated with the apparent binding. I can then remove the compensating device and check it.
Do you know of a source other than MB for the test guage used to measure the height of the compensating device?? According to the MB manual it would appear that you need to spin the engine to achieve oil pressure before measuring the height- something I can't do with it on an engine stand; I assume you have to wait until the engine is back in the car to check that.