Get rid of that bump and go trimmer head! What headaches! Take it in and get a 'fixed head' for that trimmer. Get rid of the shield. The shield is supposed to be for safety but it is hard to see exactly what you are doing and I think that is far more important and safer to see what you are trimming. I did this for a living and almost! went into competition with my little weed wacker! All my trimmers were fitted with fixed heads and shields removed. One has to be very vigilant the direction they chose and to make sure no kids, no pets, no windows are in that path and continually check. Shields just make for a false sense of security.
ALWAYS WERE SAFETY GLASSES. ALWAYS.
For fixed heads one needs to cut lengths of line, fit them through the holes that are made to hold onto that line, then cut as close as you can to equal lengths. Pull them together above the head (where the bump and go used to be) as centered as possible and cut to 4 or 5". The equal lengths or weights the trimmer has to spin is so important for the life of the motor and the precision of cutting that I also take that trimmer, turn it upside down, turn it on. Then on concrete or a big boulder (making sure where the lines are throwing) touch the lines lightly on the surface. You'll hear the change in RPM go up as the two lines become perfectly equal. The length of those lines are usually no more than 4" each. Any longer and your trimming will be out of control. Again, look where the line is tossing!!
DO NOT USE WIRE...you need to use the plastic!! Get the star cross section. It is imperative that you use the plastic, there is no way to get the lines equal and when pieces of wire go flying, very dangerous. I've never used wire.
And wear safety glasses!! Watch for kids, people, pets and windows. Those tiny little rocks become gnarly rockets. Get used to trimming (edges of lawns) on both sides to be able to change your direction. Mow your lawn first, then trim edges making sure the height of grass is the height you've mowed the rest of the lawn. No shorter than 3"!!! Do the trimming next to concrete last as that melts your lines and make for more change outs. Find the perfect length of line and cut 3 or 4 lines to loop in your belt loop and take with you. Also take a small pair of cutters. Be precise with your gas and oil mixture! Do not guess. And never use gasoline with ethanol!!!
And wear safety glasses!! Grins, sorry, but I had two of my guys, each took his glasses off when he went around the corner and each poked an eye out. Kids...sometimes the more 'parent' one is the more childish they become.
