Hi, thanks for the reply.
In the mean time I have moved the emitter from GPIO2 to GPIO5 (of course using another one from the same batch) and it has now been working well for over a month.
GPIO2 is notes as TXD1 and what I can find is that it might sometimes send signals over the connection at that might be killing the emitter.
If for some reason it does fail again I will try your suggestions but for now it finally seems to work in a stable setting.
Thanks for the great article and solution!