The typical board-type FPV camera is quite vulnerable, especially to moisture.
It only takes one blade of damp grass to get inside the frame, and will temporarily stop the camera from functioning properly.
To improve the board’s resistance to moisture getting across the SMD components, both sides of the PCB are covered with a protective lacquer.
Any well equipped electronics work bench should have a maggy lamp, and it makes working on SMD boards much easier. This maggy lamp is from Jaycar.
First, clean the board with IPA cleaner and a soft toothbrush.
Stubborn reside that can build up in between the IC pins and components is rubbed -lightly- with some steel wool. Ensure you have brushed away any remnants of steel wool.
Connectors and the lens are covered with masking tape:
Both sides of the board are covered with spray lacquer:
Hard to see in the photo, but several light coats are applied to each side:
This should stop those damp blades of grass from shutting down the camera, when coming in for a landing.