I use a 1/2" 18-8 stainless steel nut to check magnetism. Not nearly as magnetic as pure steel or iron but if it doesn't adhere tightly, the magnet ain't magneting.
Ummmm, errrr, Ohms law, folks. High voltage but no amperage through a supposed "fixed" resistance that is for some reason too high or just plain open circuit? I've seen shorted electromagnets, then I have seen high resistance wire to magnet lead connections. The 18-8 stainless magnetic test plus amperage measurement at full voltage is a viable test. Each magnet's conductivity should be tested individually. I started using JB Quick Weld as a strain relief at the wire lead magnet interface. Beats me why the wire strain reliefs at the backing plate didn't do the job.
