I had the same thing.
oil in plug wells weakened the leads so much that it eventually snapped. I did not notice the fact that it was running on 5 cylinders until it was too late and the dispack died.
got a pattern part replacement dis pack from autovaux for £55, 2 extra long leads from halfords and 2 lead adaptors. I had the new dispack fitted, not where it is supposed to be on the back of the engine, but instead on the top of the engine wedged in next to the oil filler neck. this changed an 8 hour job of screaming and shouting at the stupidly badly placed dispack into a much shorter and easier job.
placing the dispack here also means that if my HBV splits again the water wont drip onto the dispack as it is located elsewhere.
the other thing to check is your HBV, it might be that your HBV has split, leaking water onto your dispack causing a short. are you leaking coolant? do you get whisps of steam coming up from the driver's side of the skuttle??