this is of course actually a composite of two photos - one normal exposure with the flash disconnected, one of it firing shot through about three feet of ND filters.
as for the repair, it was actually pretty simple - the original problem was that the right-hand flashtube wasn't firing, so I took the flash apart (don't try this at home!) and was able to diagnose the problem to the associated trigger transformer's secondary being open circuit. i believe that when i got the flash that the right-hand flash tube's trigger pin wasn't connected properly, so i assume what happened is someone noticed the right-hand flash tube wasn't triggering (because the tube was broken), replaced the tube improperly, test-fired the flash with no trigger connection on the offending tube (this kills the transformer), and then sold the flash when the new tube didn't appear to fix the problem, though that's pure speculation. hopefully it gives me another 30 years of quality illumination for the trouble!