Set yourself up with 10 x spare sets of Mirrors for your new Firefly Level, so you can keep it in tip-top condition no matter what the working environment?
The Mirrors are easily replaced using the Allen Key situated in the Built-in slot in the V-Grooved Base of the Firefly Level. Simply remove the two screws in each of the PlumbView Retainers to release the damaged Mirror, and replace. The EndView Mirror is released via the Side screw, which is fully threaded, so it will be slow to remove and refit! Then just separate the EndView Adjuster down the centre to release the Mirror. Reverse the process to refit.
NOTE; Please do not over-tighten the screws, remember you are only screwing into Plastic!