Why does the VPI motor thump

Why is it when I turn off my VPI motor I hear a thump through the loudspeakers? The only direct connection to the stereo is the belt.
I mute my phono pre before turning on the TT, so I have no idea if my TT would "thump" if my phono pre was not muted.

More importantly, ... I have no intention of "testing" my set up to see what would happen if I didn't mute the phono pre. Why would I want to take a chance of damaging a speaker or downstream component because of a TT thump or transient or accidental tone arm drop??

So what if the TT thumps when switched on. What's the issue?? Who cares? Why is this even a question?
People care because it's annoying
My Classic had no problem with ASR integrated amp. When I swithced to Lamm, I had the thump problem. My local VPI dealer
just came over and change the capacitor for me. If I remember properly, it was just a capacitor with a little clip on thing, took all of 10 second to change it but it has to be done from the underside of the turntable. No more problem for a long time now.
But Zavato ... why aren't folks using the mute button to protect their systems from such transients??
It's not a matter of not wanting to use the mute, sometimes you just forget that little step and hit the off button on the motor - then THUMP!!!