To ask what happens to prelit trees when the lights break?

[Ninoo25]

Does anyone have a prelit Christmas tree? I like the idea of not having to wrangle with the tree lights and so have been looking at the prelit trees and have seen some nice realistic looking ones online.
I’ve never had a prelit tree before and was wondering what happens when the lights break? Do you just replace a bulb? Or the whole lights? Are either of those things even possible?!
Does anyone have one and can they tell me if they’re any good? Thanks x

We've had one for a number of years and the odd branch is starting to go out. The last year or two we've done strategic placing of branches where the lights have gone out but this year I've bought some lights to go on it. I've ordered some of those cascade lights where a ring goes over the top of the tree and strings of lights come down. Hoping it will fill the gaps and be extra twinkly where the lights still work!

Ours is fibre opttic with one bulb, had it about 15 years and I think its still on the original bulb.