Frank,
I am completely with you on this one being life is far too short to bother with the single cap (especially when the prices are relatively cheap). However, just recently I walked into multiple 800kVAR banks each built out of 12.5kVAR caps, and the air may have had a distinct odour of unease if I had uttered "oh, lets just replace them all to be safe", especially as he only wanted to know if any were on their way out.
I must be an oddball (ok, ok, correction; I am an oddball) as I never use a screwdriver to discharge a cap (I don't like the chunks it takes out the side - secondly, all my screwdrivers have insulated shafts so I can't do it anyway). They say it can damage the cap when forcing it to dispense its energy so violently. I tend to use a lamp (not quite a 1000 ohms, but still a form of current limiter). I've also witnessed capacitors that manage to revive some charge sufficiently to test one's sense of humour when closing the circuit with a hand across the terminals!
I'm not a fan of motors so don't play with them if I don't have to, but could see if a winding or start-run switch was open circuit, the cap could hold a charge - but new EN rules state that such caps must have discharge resistors in them. Bang goes that test!
M.
