At long last my 156 is back on the road and just passed the MOT. The crank problem was found to be caused by the Woodruff key slipping in the slot causing the cam gear to move which in turn caused the bottom pulley to run out of true. The engine management light came on because the cam belt jumped a cog or two. So the a secondhand engine was fitted (with 98000 on it rather than my original 166000), the turbo was rebuilt, the rear suspension and springs replaced with Konis, front springs and one top wishbone replaced, new aircon condenser, new battery, my alternator was only a couple of years old, clutch slave cylinder only a few months old, obviously new belts, gaskets, injector seals, oil filters etc. This equated to 43 hours of labour and a sharp intake of breath when receiving the bill.