St rr evo meant richen your hi and low speed needles a bit. If you think of the face of a clock having 12 hours, backing off 1 hour is turning the low or hi speed needle counterclockwise by 1/12 of a turn. Backing off 2 hours means ccw by 2/12 of a turn. Leaning 2 hours is turning needles clockwise by 2/12 of a turn, etc