A: At the recommended intervals, and whenever new plugs are installed in the engine, the Spark Plug wires should be checked. To ensure proper engine operation, one should look at the cables one by one so as to avoid confusing them. Grab the rubber boot, twist it a little and pull it free to separate the wire of one spark plug from its plug. Look inside the boot for corrosion which is seen as a white crusty powder. Fit carefully by pushing the wire and boot back onto the end of the spark plug. If it is not, remove it and crimp with pliers the metal connector inside the boot. Use a clean rag to wipe off all dirt and grease along its entire length of wire. Check for holes, burned areas, cracks or other damages. Disconnecting from Distributor Cap check for corrosion plus tight fitting. Take back into place on distributor cap again. At both distributor and spark plugs make sure you securely fasten each remaining wire one at a time. If you need new spark plug wires buy an exact set for your specific model of engine. Take out each wire individually replacing them in order so that correct firing is noted before removal starts.