could have saved my life.

I was in my workshed which is about 60 ft from the house drilling some
aluminum. I got a faint tingle in my hand, I touched the case of my
drill a couple times and didn't feel any thing, so I started to drill
again. I noticed the tingle again, I went through this a few times until
I decided there's a problem. The tingle was at a tiny red spot on my
finger, I later removed a small metalic sliver. If not for the sliver I
probably would not have noticed the missing ground, for I don't know how
long.
The drill motor is a 3 wire system, hot, neutral and ground. I had it
plugged into a GFCI. I unplugged the drill and pushed the test button.
The GFCI didn't pop. I retrieved my DVM and tested from the drill case
the the dirt outside the door, it was about 80v. I then tested from the
Hot to the ground at the receptacle, that was about 20 v. I moved to
another Receptacle closer to the house, same thing no ground connection.
I moved up to a receptacle on the outside of the house on the same line,
again no ground connection. Inside the garage, no ground connection. I
opened the circuit breaker box and checked the ground wire, it is good.
So, in my attic between the CB box and the garage there must be a
connection box where the ground has opened up.
Followup tomorrow evening.
Mikek