You wake up to a pouring rain storm the best music to your ears is the constant click on and the moaning tune of a working sump pump.  This pump has been working through every rainstorm for more then I can remember.  This makes me think it may need to be retired and a new one put in its place.  This thought gives me some pause to ponder.  Its working so well.  But the only way to know it needs to be replaced is when your basement is feet deep in water.  So replacing when it is still going strong doesn’t follow the old say of- if it’s not broke don’t fix it.