1. Check if the top cable glands are tightened (microphone and solar panel). Hold the base of the gland with an adjustable spanner or pliers to prevent the nut on the inside from coming loose. Tighten the top compression nut.
2. Check if the vents are tightened (these look like hexagonal bolts). Tighten these vents as much as possible by hand, or tighten them carefully with tools using little force. This is in order to prevent damage to the silicone seal.
3. Check if the PCB shows signs of corrosion. Corrosion marks are white/greenish and can be found on and around soldered seams or other bare metal parts.
4. Check if the foam lid seal is still in place and free of damage.
5. Check if the brass M4 threads on the lid have been pulled out.
6. Torque the lid to 1 Nm to prevent damage to the M4 threads.