https://vertikal.net/en/news/story/47254/dropped-counterweight
Didn't think that possible unless something catastrophic failed
operator error .... top slice got snagged on the lift rams probably and he didn't notice

to mount/dismount the slices you slew over rear, circa 175 degs, drop the lift rams, slew a further circa 5 degs, into line with the chassis and lift the slices off the bed carrier ..
de-mount is a reverse procedure, but if you slew that 5 degs, off centre line
before the lift rams are
fully retracted it's possible to catch the top slice and if he's in a hurry/not observant enough, he can set off with it balanced on the lift ram tips - 'til summat like a bump in the road or whatever dislodges it and BANG
the holes in the slices on some machines are 'keyhole' shaped and you can pick up 1/2/3 slices, depending on how you want to rig
next time I'm out with Russ I'll vid it ... have to be precise with the ballast