We have serviced thousands weed control sprayers over many years in business. There are 3 things we have seen that will reduce problems in the field and extend the life of your weed control spray rig (or pest control, golf course sprayer, etc.). This is true whether you are talking about a power spray rig, a B&G or a backpack sprayer.
1. Take the pressure off. When you are done spraying, release the pressure. Squeeze the handle of your spray equipment so that the system is not under pressure. If you don't want to waste the material, spray it back into the tank. Your equipment will have fewer breakdowns and will last longer if you remove the stress of constant pressure from the spray components. Never store equipment overnight under pressure.
2. Good filtration. More problems are caused by filtration issues (clogged filter, no filter, too coarse/too fine filter) than by any other cause. Make sure you have the correct filtration and make sure your technicians are checking and cleaning the filtration periodically. You should set the period based on your experience. The labor cost of checking too frequently is less than the cost of not checking frequently enough (downtime, productivity, repair cost, etc.).
3. Clean your system out. Rinse your system with clean water periodically to remove old chemical buildup, debris, etc. Chemical buildup & debris can clog your filter, starve your pump, damage spray tips, and play havoc with other components as well. All of these items fall into the category of "not good". When in doubt, rinse it out. Be sure to follow all labels and laws when cleaning out spray tanks.
Hope this helps. Happy Spraying.