Reel mowers will occasionally need to have the blades adjusted. This is not a difficult task, and it takes only a few minutes about once a year. The adjustment will set the correct spacing between the blades (on the reel) and the cutter bar (on the mower frame). You will find two types of settings. Regular reel mowers are set so that the blades brush against the cutter bar, making very slight contact. These mowers make the traditional snipping sound as the blades turn. Newer "silent" mowers are set so that the blades are extremely close to the cutter bar without actually touching it.
Set the mower on your workbench in good light. Turn it so you can work from the back of the mower.
Locate the cutter bar and the adjustment screws for the cutter bar. These are usually on the bottom at the ends of the mower frame. Some mowers have two screws, one on each side, and some mowers have four screws, two on each side.
Use the adjustment gauge that came with your mower. It is a thin metal strip about one inch wide and five inches long. If you can't find it, look in your owner's manual; some companies fasten the gauge into the manual with tape.
Slip the gauge between the cutter bar and slowly turn the blades. Check all points up and down the length of the cutter bar to see if the blades are too far away or too close.
Adjust the screws by making tiny turns 1/8 or 1/16 inch at a time. Keep the adjustments minute. For regular mowers the blades should just barely brush against the bar. It should be a smooth, easy movement. On silent mowers, the thickness of the gauge (usually less than one millimeter) is the distance the blades should be spaced from the bar. Silent mower blades should not contact the cutter bar. Recheck along the cutter bar, making sure the spacing is even the entire width of the mower.
Use a newspaper strip to test the adjustments. Carefully feed a long strip about two inches wide through the turning blades. When the blades are properly adjusted, they will cut the newspaper strip cleanly, with no grabbing or folding.