I hope I didn't make Rob mad at me. sure hope he helps finish this.
I'm not mad. I'm just concerned. I've done this stuff a long time and I can see you have limited experience. That's fair enough everyone is in the same position at some point. This job is risky you can get electrocuted. If your mind is thinking about how to set the meter you aren't thinking five steps ahead to avoid the dangers.
Imagine going on an climb to Mt Everest with limited experience. It doesn't matter how experienced your guide is, you are at extreme risk. Your guide can tell you stuff but if you make a mistake tying one of the knots you will be in trouble. The guide's not only thinking about the knots (which he can do easily) he's thinking about checking the knots and thinking many steps ahead, making choices so he doesn't get into trouble. If you have limited experience you might not even be aware of the danger at all. This is how you get in trouble.
Here's an example where you are close to danger. It's in the area of the power supply where
you are making measurements. It's very easy to slip or make a mistake.
Click to enlarge:

I might add the unit is not Earthed. It uses a two-wire mains cable.
Also the mains inlet is just knotted and can push-in and get amongst the 1kV stuff.
That old mains cable is not rated for 1kV.