Thanks for suggesting that, Dave.
Thought about that, but was discouraged by the first attempt (Quite scary to have distorting tracks on a current project)
But now I just tried it - and it works. So card should be good.
Took the bold move to then insert my old accel card in the upper slot (0) and magically all cards are now working, so PROBLEM SOLVED.
I am guessing that I might not have installed the new accel card properly the first time around. Flex might not have been sitting right, og a reseating of the cards might have helped
There we go - HD3
Thanks again