Sometimes, you don't have the time or correct parts to fix a problem. If I am going to create a hack to fix a problem temporarily, I like to ensure that it is easily reversible and will cause a minimum of damage to the game in case it goes wrong.
With a time crunch before a group of newcomers to pinball came over, I had to correct a flaky switch that incremented the score on an older machine.
A freely rotating contact on a leaf switch can, sometimes, be soldered in place to allow for continued operation without a replacement switch at hand. This is a very easy hack to reverse, as I simply have to replace the switch and the issue goes away (I'll be doing that soon).