What are you calling "dangerously low" oil pressure? My 116 drops down to a little less than .5 bar at idle, and the manual says .3 bar is OK so long as it rises when the RPM's come up. Can you see the tubes "peeing" on the cam lobe viewed through the filler cap hole at hot idle? If you can, you're probably OK.
The tubes are metal - like a copper alloy.
I for one don't think the cam oiler assemblies have much to do with oil pressure. But while you've got the covers off, why not replace the caps and all the little plastic holders on the cam towers?
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe