The 5mm ball fell off in the test head
The solution is as below:
Remove the test head from the shelf,anticlockwise the screw, you can see the oil overflowed,draw out the oil with the needle and take out the spring,keep to draw out the oil until you can see theφ5mm ball groove,use the light to check if theφ5mm ball is moved and not in the ball groove,if theφ5mm ball is in working condition,normally if the pressure lever stick not working, theφ5mm ball is moved,shake the test head to let theφ5mm ball back to the ball groove,and then filled with the oil slowly to avoid entering the air ,put the spring back, and clockwise the screw,fix the test head back on the shelf.
Tools φ5mm ball not in ball groove