Why is air escaping from the hole in the regulator of my Underhood or Gas Driven (G300003) Compressor?

Air escaping from the little hole beside the adjusting screw in the cylindrical regulator cap is normal.

This hole must be free and clear in order for the regulator to function properly.

If this hole is blocked, the typical symptom is the system will build air once when the system is turned on, but will not build pressure again when that initial air charge is used.