taking your time to make sure you inspect everything carefully

1. if you have unusually good access and unobstrcted view, like-new plug wires and wire slack permits,you can carefully snap open clips holding distributer cap on, carefully lift it just enough to examine inside the cap and rotor looking for moisture, corrosion,cracks & carbon tracking using compredded air,air duster spray can or pistol type hair dryer blow dry inside cap wipe and/or dry it w/paper towel If you have aerosol spray contact cleaner\dryer you can use it

otherwise proceed with inspection as follows

2.remove one plug wire from cap
mark it with its number with masking tape
disconnect other end of this from its spark plug
remove debris & clear area in around spark plug
remove plug & examine electrode: write down down plug condition if its less than perfect
wipe connector dry or clean it with steel wool
reinstall plug,reconnect wire to spark plug
proceed to next plug wire
repeat above

dry and inspect inside distributor cap and rotor for moisture,cracks and carbon tracking
spray a little contact cleaner or 99% isopropyl alcohol inside (or on paper towel and wipe inside dist cap)clean dry thoroughly with air/air duster/hair/dryer,
finally reinstall rotor, cap and wires carefully.

If you find cracks, corrosion or carbon tracking in dist cap:replace with
premium quality cap +rotor with brass contacts (Duralast Gold $15- $30)