I don't think the problem is with the platter, though shifting to an aluminum platter will change the sound. IIRC the Well Tempered has an acrylic platter and the VPI Mk iii has a combination platter with acrylic on top. So acrylic should not be the problem. I, for one, believe that the movement back to an all metal platter was a step in the wrong direction.
Make sure that the VPI bearing has had a good lubrication in the not too distant past. The VPI can also be improved if the bearing is replaced with a Mk V bearing and removal of the tripod. The factory may have some old bearings lying around. A 300 rpm motor and flywheel combo would also help.
But I agree that most likely there is a mismatch between the Koetsu and what comes after it.
Make sure that the VPI bearing has had a good lubrication in the not too distant past. The VPI can also be improved if the bearing is replaced with a Mk V bearing and removal of the tripod. The factory may have some old bearings lying around. A 300 rpm motor and flywheel combo would also help.
But I agree that most likely there is a mismatch between the Koetsu and what comes after it.