How to Swap Markbass Bass Amplifier Head Units in a Markbass Combo Amp

I remove a Markbass Combo Head II (Little Mark III) from a Markbass CMD121 12" Combo amp, and install a Markbass Little Mark Vintage amp in its place. As noted in the video, my only revision to this procedure would be the recommendation to attach the 2 top plates to the new amp chassis before cutting the threads on the chassis holes. This way the old threads on the top plates and the new threads in the chassis holes are all continuous. I could feel the resistance of the screws re-cutting threads into the chassis as I mounted the amp since I didn't base the new threads' starting points on the existing threads' ending points. Not a huge deal, it worked fine, but a bit of a process improvement.