Did you read the earlier replies? I gave an example of a Ball Fireman that is 15 going on 16 years old, and is nowhere near in need of tritium replacement, nor will it be in a state of "no usable lume" four years from now. Of course any watch that needs to be opened up should also be serviced, but owners certainly won't need new tubes "every 10-15 years"--not even close. If you want the hands and dials replaced, of any brand, you of course must send it to that manufacturer, but if you want just the tritium tubes replaced, of any brand, you could either send it to the original manufacturer, OR, send it to a third party outfit, such as Bonding, who will remove and replace the tubes from the hands and dials of ANY watch, for a reasonable price. To refresh your memory, here is another shot, taken recently, of a 15 year old Ball Fireman--the age which you state is well into its tritium tube replacement date ("10 - 15 years")...not.
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