Other than Canon, where would you send your 580exII, to be repaired?

I have two canon 580ex II flashes, which complements our 7d.  One of our 580ex II flash units does not fire, but all the other many functions on it seem to work just fine.  I could be wrong, but I think it just the bulb.  I have seen on this forum a "do it yourself" repair.  Also, on ebay there is a company which will fix this for almost half of what Canon charges.  I would appreciate your help in finding a good reliable company that you have used for past repairs.

Thank you - Phil

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