Help with Marelliplex

[Robert_A_Brady@domain.elided (Robert A Brady)]

My '74 gtv has a marelliplex ignition.  It appears, from the visibly weak 
spark and the plugs that something is wrong with it.  Before I begin going 
through the test procedure, has anyone experienced a steady weakening of 
their MarelliPlex system?  Most failures I've seen reported are of the "no 
spark at all" variety.  I would think if the coil was bad, it would be 
completely bad.  What about the control module?  Could that gradually fail, 
or would it typically fail completely.

Thanks in advance, 

bob brady, dvaroc
'74 gtv (sick)
'88 verde 

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