JB, Something sounds wrong to me, as I just took a measurement of my stock VPI Acrylic Wand's slot, and the measurement is exactly 100mm, or 4", which ever you prefer to use. And the measurement of the origin of the slot, measured from the outside perimeter of round base collar of the Wand Assembly is exactly 1/8".
So, with that being said, something sounds awfully wrong, in that the slot sounds as if it was cut much too short at 8cm (which is 80mm). That's 20mm shorter in length than the VPI Wand Slot.
Provided Lloyd made an exact clone of the VPI Wand dimensioanlly, but just from a different material (Delrin), and a narrower cut slot minus the velvet lips, I honestly don;t see why the slot should be 20mm shorter? Sounds more like you got a wand more suited for 78rpm Shellacs?
We'll wait for Rushton to chime in with his findings, but you may wish to as well, shoot an email off to the folks at Walker, they'll definitely know what's cookin.
Mark