The movement is caused by a wire heating a beam its wound upon. The wire has a yellowish spiral would fiber insulation. I've opened several to find that winding caked with black crud. Looked5 times its original size. My only guess is from tobacco smoke as its worse in gauges closest to the ash tray. Anyway,,, this restricts beam movement much like an ace bandage at your elbow. Thats why I repeat again and again. High voltage or zero ohms can get results that a proper in range test would not.