I almost lost my Zenith 19r20 Royal R down the steps. I have had this set for 15 years or so and have moved it a few times with no troubles. Well I was bringing it down the basement steps to the shop to finally recap it and to make room upstairs for my 64 Zenith Roundie so it doesn't have to sit in my screen porch overwinter. So on the way down the chassis decides To pop off the knobs and head for the floor. I managed to catch it thankfully. The sets not too big but a little awkward and heavy for the back. My leg was scratched up but I think everything else is ok. I know I never took out those screws on the bottom. So they must have been out a long time. So moral is to double check the mounting screws! And get help.