If, as I understand it, the screw in the top of your alda fell out then your way over turned it and broke it off the top aneroid inside the unit. Go to the junk yard and get another one. To take the alda off is not hard I just reach under it with a pair if channel locks and grab the hold down nut and move it enough to get it loose then unscrew it the rest of the way by hand. Diesel Giant has some good info with pictures inside the alda. When you get a replacement open the old one so you can look at the parts and see what you are effecting when you adjust it. When adjusting NEVER force the adjusting screw.

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1983 300SD
200000miles