A repair that isn't done correctly is a failure waiting to happen. Some common errors include:
Poor hygiene. Lay disassembled parts on a clean surface, such as cloth for that purpose. At every step, prevent the introduction of grit, chemical contaminants, and water. Even finger oil on contact surfaces can create problems later.
Misapplication of lubricants. No, it's not okay to spray breakers with a handy can of spray lubricant. A spray lubricant doesn't have the "body" to adhere to high pressure points of contact. Use only the lubricant specified by the manufacturer. Don't over lubricate.
Re-using old fasteners. For control wiring and other low-torque applications, this is usually acceptable. If you need more than a screwdriver to tighten the connection, replace the hardware.
Misapplication of spring-type fasteners. Belleville washers are commonly misapplied. The errors are usually over-tightening or use of the wrong size. Replace after each use with the correct size, and follow the installation instructions for a reliable connection.
Improper torqueing. Improper tightening of motor mounting bolts is a leading cause of replacement motor vibration problems. Use the torque value specified for the fasteners you’re using, not the value from a generic table.
You can prevent most "failed repair" problems by addressing potential failure causes in your repair procedures. Ask a few key questions, such as: For breaker X, what lubricants do we use? For feeder bus 06E, which Belleville washers do we use?