Yes, John, I have been there. Late one night, working alone, I decided
that I could put an upright back on its casters by myself. When the
rear wheels of the piano touched the floor it skidded forward, fell
backward against the truck and pinned me to the floor. My right leg
was caught in the truck and underneath it. There was nothing I could
do to free myself.
Fortunately, the tenants in the space next to me were working late and
heard me yelling. They broke in the front door and freed me. I was
not hurt, just angry with myself for trying that stunt alone.
Here in San Antonio, many years ago, a man was trying to move an
upright by himself. It fell backwards and crushed his five-year-old
son to death.