Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any 'hickups' (be sure to completely shut down the air compressor!). Check the isolation of the motor windings.
[pdf] use caustic soda solution (Concentration 8-10%) Heat to 60℃ and soak the handpiece for 24 hours. cooler Use a high-pressure water gun (pressure>15MPa) to back-flush the copper tube. replacement All-oil sealing ring Avoid corrosion by residual cleaning agents.
[pdf] use caustic soda solution (Concentration 8-10%) Heat to 60℃ and soak the handpiece for 24 hours. cooler Use a high-pressure water gun (pressure>15MPa) to back-flush the copper tube. replacement All-oil sealing ring Avoid corrosion by residual cleaning agents.
[pdf] 
