Off the shelf products don't always meet expectations and this was the case with a Park Tool 106AC quick release collar owned by reader Bart. He sent a video showing his modification, and he introduced it via the following text in an email -
I've been frustrated with the Park Tool 106AC quick release collar that I decided to modify my own using a ebay seatpost clamp.
I spent about $26.xx on the 106-AC collar and I customized/ghetto/hacked my existing one for less than $2.00
I figured this could make a cool addition to your site and if your users want height adjustment on their Park Tool PRS-9 bike stand...my video shows how to do it.