Please follow the following procedure:

(1)  Check that the bulb is well within its rated lifespan.  The published figures are guidelines only so although a 400 hour lamp will usually last 500 - 600 hours, if a bulb does fail at 300 hours it probably just needs replacing. 

(2)  Disconnect the power cable from between the lamphouse and the power supply.  Inspect the cable throughly at both ends and if any of the pins have become unseated then push them back and ensure that the cable is free from stress when replaced.

(3)  Taking care to wear protective eyewear remove the bulb from the lamphouse following the instructions supplied with the system (copy available on this website).  Clean the insides of both electrode holders with some fine sandpaper (even a small amount of corrosion can cause striking problems).

(4) If the steps above don't work then either contact us to arrange for a return or if you would prefer to try to avoid this then it is worth widening the spark gap between the coils by a few mm.  This gap provides an alternative route for the high voltage to bridge in the event of a failed bulb. Over time the impedance across the bulb can increase and the required size of the gap needs to increase slightly to ensure that the path of least resistance is still across the electrodes in the bulb and not the safety spark gap.  To widen the gap either snip the end off one of the wires or bend it slightly to increase the gap between the tips.