Reading your boost with a gauge from the banjo bolt and what the over boost circuit and alda do are different issues than not having any boost at all. When I had over boost cut off problem, I hooked up a boost gauge to where the threaded plug is on the side of the manifold.

If the rebuilt turbo is spinning and you have no boost, I would check the waste gate adjustment and valve under the plate opposite where the diaphragm is. Maybe the valve is stuck open, or the adjustment is so far off any amount of boost opens the waste gate. My waste gate valve was stuck closed (leading to the over boost protection and fuel cut off). I never messed with the banjo bolt, the line running from it to the over boost circuit, or alda. None of them were the problem.

I think I remember someone here, a long time poster, who has owned numerous Mercedes diesels saying he had never messed with an alda. Anyway, everything downstream from the banjo bolt deals with the boost that you do have, but doesn't affect whether you have boost or not. If you have boost but can't read it from the line coming from the banjo bolt on the back of the manifold, then your probably plugged or have a leak somewhere.

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1985 300TD, 375,000 mile daily driver