speedotron issue

I'm having an issue with my trusty speedotron unit at the moment. as discussed in another thread. it's plugged in every few months to make sure the capaciters are charged in kept in good working order.Last night however. the test flash withan M11 head gave nothing but a weak sounding 'pop'. it seems dead. what's your experience?what can I try next?

problem solved!a different head on a different port worked. the wonders of electronic engineering.