(4) If the tube head drifts, the brake is malfunctioning. Adjust the brake with
an open-end wrench. See figure 1-7.
Tighten the brake firmly but gently.
(b) Check the various arm positions for drifting.
Figure 1-7. Open-end wrench 13mm--`1/2 inch.
Inspect the control and the tube for a burned light bulb.
Inspect the hand control cable for cuts and nicks.
The power supply must be grounded.