Needle Scaler on the Fritz

My needle scaler suddenly stopped working. It just blows air out the exhaust port. Can we fix it? And while we're at it, how does it work?

• #autos_vehicles
• #needle_scaler
• #air_hammer
• #needle_gun
• #rattle_gun
• #pneumatic
• #air
• #valve
• #tear_down
• #repair
• #fix
• #clean
• #lap
• #lapping
• #rust
• #piston
• #magic
• #how_does_it_work
• #drawing
• #tailgate
• #poppet