The Bolens BL100 gasoline powered string trimmer does an adequate job of trimming grass around walkways planting beds and other spaces that are too difficult for lawn mower to mow. The string is released from a spindle at the bottom of the trimmer by "bumping" the machine on a firm surface. Just like any other string trimmer, you can only "bump" the trimmer so many times before it runs out of string, and the string must be replaced.
Remove the cutting spool from the trimmer following in the instructions in the owner's manual.
Unscrew the bump knob with one hand while holding the outer spool with the other by turning the bump knob clockwise. Inspect the bump knob and the bolt inside for damage. If the bump knob is damaged or the bolt does not move freely, replace the bump knob.
While holding the outer spool with one hand, pull the inner reel out with the other hand and remove the spring from the inner reel.
Clean the inner reel, spring, shaft and the inner surface of the outer reel with the shop rag. Inspect the teeth on the inner reel and outer spool for damage or wear. Use a small file to remove any burrs on the teeth. Replace the reel and/or spool if they are to warn or severely damaged.
Feed each end of a 20-foot length of trimmer line into the round holes provided in the inner reel or a 10-foot length of split trimmer line into the right oblong hole in the inner reel. If the 20-foot length of line is used, pull both ends equally through the inner reel until the line is tight. If the 10-foot length of line is used, insert one end into the right oblong hole and pull the line through the reel until approximately four inches remains. Insert this end into the left oblong hole and pull the long end of the line to tighten it. Split the first six inches of the long end of the split line.
Wind the line around the inner spool in the direction indicated by the arrows on the inner spool. Make sure the line is wrapped in tight even layers by pulling the line tight and holding a finger on the line as it is being wrapped around the inner spool. Do not allow the lines to overlap.
Insert one line in each of the two holding slots on the inner spool. Install the spring in the inner spool. Feed one line through each of the islets in the outer spool from the inside of the outer spool. Insert the inner spool into the outer spool and hold them firmly in place with one hand while pulling each of the strings to release them from their holding slots in the reel.
Install the bumper knob by turning it clockwise, tightening it securely by hand.
Install the cutting spool back on the trimmer following the instructions in the owner's manual.