I had a 1200gs 2006 but never had that problem- so I just called BMW Ocean ( very good guys down there
They tell me they have never changed one of those parts or heard of one failing-and suggest the following
1- check the IN and OUT pipe of your oil cooler (they should both be hot, the IN side, of course, hotter so mind your fingers! - if one side is cold- the oil cooler is at fault
2- If you have a stone protector in front of the oil cooler- this does reduce airflow to the oil cooler-
3- The assumption is made that your bike has the right volume of oil & of the right spec.
4- has the bike fallen over lately? could you have squashed one of the oil pipes?
If you follow Javier's excellent link, (page 3 the part being held up) that brass part is called EXPANDING ELEMENT # 15 on diag could
be the culprit but BMW Ocean don't think so. If you do decide to undo it, it's 2 bolts but be aware there is a spring (14) just below it)-