Remove the power cover of the engraver (As shown).

Measure the voltage of the air pump’s plug (as shown).

• If the plug voltage reads 12V, replace the air pump with a new identical one.
• If the plug voltage reads 0, check the continuity of the wiring from the relay to the air pump.

Set your multimeter’s beeper on.

Check the continuity between the relay to the plug of the air pump (as shown).

Check the location of wiring disconnections and repair them.