Rick,
The 107 maintenance manual says to remove the dash to service the actuator, DON"T DO IT. You can get to the actuator thru the center dash openig if you remove the climate control unit, radio and console it is on the upper left of the opening there is a rivet holding the arm to the top of the actuator this has to be drilled out, I used a #10 drill bit. if you get the parts and the tool to disasemble the actuator the new diaphragm should be a snap to change. On my 560 it is a dual actuator so you have two pieces to remove. Make sure the new actuator is seated properly or you will be back where you started. You will have to use a machine screw w/ locknut or a rivet to hold the arm on the actuator, don't over tighten or it may bind up. Putting everything back together is a snap. I did mine last week, so if you need any guidance let me know.
Good Luck
Frank

86 560SL
94 Blazer S10