A friend of mine asked me to see if I could fix one of his Yamaha S250X P.A. speakers for a concert this weekend.He said it was crackly and he could hardly hear anything coming through it and admitted that he had been running them flat out when it failed.I took it apart and tested the components in the crossover and the drivers but everything was OK except for one of the bulbs was blown in the speaker protection circuit which comprises of two sets of interior car lights in parallel and series. So I thought the signal power isnt getting through the single bulb properly and because theres no markings on the bulbs to find out what value they are to replace it he asked me to solder a 1 amp fuse across the blown bulb? I did that but Im having second thoughts now. What if the two bulbs by itself are a weak link? Should I have soldered the 1 amp fuse across all the bulbs? Ive taken a photo of the bulbs but I cant upload it here for some reason so I drew a diagram in Paint and I cant upload that either? Any ideas, suggestions?