You don't have to reburn the bootloader, but I guess you can do it if you want to.
The stock examples should just work, as long as you match the frequency settings.
I'm really having a hard time trying to understand how they worked fine before I bagged and shipped them, and now they don't, you know what I mean?
Frankly I am fairly convinced there is nothing wrong with them, as proven in other cases where the user was absolutely certain they were, but turned out they were not. It's almost always something very minor, either something missed in the sketch or some procedure error.
Could you post a picture of what/how you soldered them?