Rather than upgrading the VPI to Mk.4, look for a TNT-3/4 platter (7/8" lead-lined aluminum bottom, 3/8" Delrin top layer) or TNT-5 platter (5/8" stainless steel bottom, 7/8" Delrin top) and bearing.
The subchassis of the VPI has a 1" hole drilled for the platter bearing, and some of the TNT bearings are also of 1" diameter (others are 1.25"), so will slide right into place. Either choice under $500.
For the Grado/motor hum, there are shielding materials made than can be wrapped around the motor.
Remove the stock suspension springs, place a set of Townshend Seismic Pods under the subchassis (sitting on the shelf, not the HW-19 wooden outer base).
By the way, the HW-19 Jr,. and Mk.1 and Mk.2 had steel painted black subchassis, the Mk.3 and Mk.4 unpainted stainless steel. The Jr. and Mk.1 have a 1/2" layer of MDF on top of the steel, the Mk.2/3/4 1/2" acrylic.
There is a guy parting out an HW-19 right now (I don't remember where. A Hi-Fi Shark search should lead you to it), the base and subchassis separately. And on USAM there is an HW-19 upgraded with a TNT-5 platter and SAMA (Stand Alone Motor), asking price around $2200.
The subchassis of the VPI has a 1" hole drilled for the platter bearing, and some of the TNT bearings are also of 1" diameter (others are 1.25"), so will slide right into place. Either choice under $500.
For the Grado/motor hum, there are shielding materials made than can be wrapped around the motor.
Remove the stock suspension springs, place a set of Townshend Seismic Pods under the subchassis (sitting on the shelf, not the HW-19 wooden outer base).
By the way, the HW-19 Jr,. and Mk.1 and Mk.2 had steel painted black subchassis, the Mk.3 and Mk.4 unpainted stainless steel. The Jr. and Mk.1 have a 1/2" layer of MDF on top of the steel, the Mk.2/3/4 1/2" acrylic.
There is a guy parting out an HW-19 right now (I don't remember where. A Hi-Fi Shark search should lead you to it), the base and subchassis separately. And on USAM there is an HW-19 upgraded with a TNT-5 platter and SAMA (Stand Alone Motor), asking price around $2200.