1990 300E

Anybody has details of fuel distributor? On my mechanic's suggestion, I opened the top portion of fuel distributor. I saw small pin ( push/pull type) at the bottom of top block. Around this pin, there is threaded ring. I didn't see any o-ring. Is this pin called plunger? What is inside the hole in the lower block of fuel distributor?

Basically, I sprayed WD-40 around the pin to eliminate the possibility of pin sticking. Although, when I opened the top block, the pin was free and not sticking. Also, I tried to feel the component inside the lower block. Is there any thing inside the lower block which I may have moved when I tried to feel it using a small screw driver?

Previously, the car used to run when I pour little fuel in air intake, but now, it only cranks & does not run. What did I do? I am trying to undo things, so that at least I can be able to run the car & take it to shop.

Please help.

ps: I have been struggling with this problem for almost a month. Get me out of this misery!