arrgh! ignition coil failure!

[Hhchicken1-at-xxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

This may be a bit off topic, but I hope someone can help me get the power 
supply for my TC back up and running... 
While running it this morning the ignition coil system (2 in parallel, see my 
earlier post "First light with car ignition TC") suddenly stopped.  I cannot 
find a single component in the 240v circuit that has failed - the series cap 
checks out, so does the dimmer switch and fuse. I can only get sparks when I 
switch the circuit on, normally just one.  I'm at a loss as to what's broken! 
I'm pretty sure the coils work OK cos I can get sparks from them during the 
moment when I switch the circuit on, but once it's on it does nothing.   
Please can somebody help me! :) 

Thank you, 
      Henry Hallam