Even without a lead to the test socket, you should be able to hook up a DMM with a duty cycle function to the positive lead to the frquency valve and get a on/off reading. Assuming of course that there is a frequency valve.

There should be a hole in the air cleaner where you insert a long-arm 3 mm allen wrench to adjust the mixture.

__________________
Chuck Taylor
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