Thing to do is disconnect from the dizzy end and earth the king lead (LT) that goes from coil to dizzy, then with an assistant turning the engine over you should see a healthy blue spark. It's actually when the primary voltage collapses I.E when the ECU breaks the coil's earth it creates the high voltage transmitted from the secondary field.

When this happens it's usually the inducive module thats faulty that causes the problem on the distributor that is assuming ERST has this as I am not familiar with them but that would explain your wires on the dizzy.

Martin