That used to be true but the rules changed when rare earth magnets became available - they're humungously strong, and light.
Ah - Hammond! My son wanted one for his teenage band about 10 years ago so we picked-up a part-working split M101 (I think it was) and spent many happy(!) weeks getting it going. I started-out as an electronics engineer by profession so it wasn't too bad, but I hadn't even heard of a tonewheel before we started and by the end I was intimately acquainted with every aspect of the beast. The hardest part was dealing with many broken wires, tired capacitors and gummed-up bearings. It went to Hungary when we sold it so hopefully it's alive and well and bashing-out a whiter shade of pale somewhere in Budapest. Yes, it was heavy! ... and now, back to the thread :-)