The engine in my Corvette wouldn´t work after a restoration and according to the previous owner it hasn´t worked before either.
So I consulted Pinwiki, Cliffy´s page on LT5 repair, various threads here on Pinside and some German Flippermarkt forum members to get this engine working again.
Pretty quickly we identified the DA converter AD7524 and one of the "disabling" transistors as culprits, but swapping them didn´t fix the problem. It got better as we could now move the engine by simulating the DA with a poti, but in the pin the T.16 test would still fail. The engine in test behaved pretty much like in the thread by tonycip .
The problem seemed to be on the hall offset board because it didn´t deliver an output signal the slave board could work with, but we couldn´t find a part that was behaving strangely. That was when one guy from the German forum came up with the idea that the magnet might be installed with the wrong orientation and therefore confused the circuit. I turned the magnet around but that didn´t change anything. Bummer!!
The next idea was that maybe the long sides if the magnet are actually the poles and therefore we had to turn it around along the long axis instead of the short axis as you would expect. So I tried that and believe it or not: that did the trick!!!

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Here´s a video of the T.16 test now after the fix:

So here´s an important hint for all of you that struggle with a non-working Corvette engine or those that do a full restoration:

The orientation of the magnet is IMPORTANT!!!