I had a phone call about 10:30am to say an old DC motor on another site I look after was making a funny squeaking noise....but not to panic...the Engineer has it under control.  So I wasn't required on site.  
About an hour later I get another phone call....better come over and take a peek.....bearing change & com skim didn't help any....
Nek minute, I am rushing around on a Friday afternoon second guessing to pick up supplies for a Saturday swap-over.  Went from the 50+ year old variable speed DC motor to a modern 3-phase motor and VFD.  Saturday turned out to be quite lucrative for me.  
Fixed up a couple of issues that the guys have had for 20+ years on site with trailing cables etc.....and the machine will be easier to fault find from now on. 
Best Friday 13th ever.