String trimmers are great tool for getting rid of tall grass in those hard to reach corners of your lawn. Most trimmers have a bump head to feed the cutting string so that you don't manually have to adjust it. All of the bump head feeders have almost the same basic design. When you bump the bottom of the trimmer on the ground, a spring loaded device feeds line to where the trimmer cuts. This is a simple device that was designed to reduce the time and work you use trimming.

On the Other: Bump Head Feeders All Seem to Have Problems

Unfortunately, all trimmers seem to eventually have problems with the bump head feeder. The bump head feeders on the more expensive models tend to be slightly better than on the cheaper models, but all seem to jam eventually.

Bottom Line

The bump feeders on all trimmers have the same basic design, but may not be interchangeable. All seem to eventually have problems. It is a simple device, but if your string is not perfectly loaded, or you are using a different gauge string than suggested, the bump feeder can jam. As of 2010, there are feeders that accept various gauges of string, but you will still have jams and breaks in your string. There are also several companies that offer universal replacement bump head feeders for under $20, but they are the same basic design as the originals. It seems all of them are persnickety and eventually jam.

Source:

Readers Digest: Install a Simple Stringer Head

Garden Web: String Trimmer Problems

More Information:

The Stucco Company: Who's in Love With Their Stringer Head?