Quoted from rolf_martin_062:what is meant (post-15) with "try shotgun cleaning - adjusting"
Unlike other types of guns that fire a single bullet projectile, a shotgun fires multiple pellets (like numerous small ball bearings). When the shot (proper word for the pellets) exists the barrel, it spreads out in a circular pattern. So if you fire a shotgun at a wall, you'll have a scattering of hits roughly in a circular pattern.
"Shotgun cleaning" implies a semi-random pattern of "just clean / adjust anything that *might* be related to the problem and see if the problem goes away". For someone who lacks experience cleaning and adjusting switches, there is a significant chance that this approach will introduce new problems without actually solving the original issues.