Quoted from STTNG:..I also gave the same treatment to another WW, this was put on a site & has had no issues for.
Wait for it... 4 years.
Brit thing?
Maybe it is a Brit thing (the 555's lasting so long that is) becuase the 555's that have been on any WW topper here in the US that I have ever seen WILL burn out. No option of keeping them in there at all because they won't last long without burning out into a nice silvery black bulb in less than an hour or so. Even led's will melt.
The very fact that STTNG's 555 bulbs have lasted more than an hour means something is different with his or other UK machines? Either the 555 bulbs are not the same as the ones out here or the volatage going to the lamp board is different.
Normally 555's aren't even an option, they should just not be compatible.
Interesting if there are differences in his or other UK machines which allow 555's to surivive in that lamp board.