The manual simply recommends 40 wt. motor oil, so any type should be OK. JohnK

To my mind a 2mm discrepancy is not critical, particularly if you are using the VPI gauge or something like the Feickert protractor. Both will compensate for the 2mm difference. If you really want to hit 300 exactly, there may be enough play if you loosen the screws holding the VTA assembly. You have to remove the tonearm and moveable platform, and then it's trial and error how much to move the assembly. JohnK

Contact Steve at VAS audio. He does great work. https://vasnyinc.com/ JohnK

What is the issue? Mounting hole size? Mounting distance?

Regarding whatever alignment the VPI gauge results in, I recently checked it against the Feickert NG protractor and it seems closer to Baerwald than Stevenson, but not exactly either. JohnK

You can use superglue for the Periphery ring, but since VPI essentially gives away new ones I'd just order a set. JohnK

Setup for that arm is described in the HRX manual: https://www.vpiindustries.com/_files/ugd/5e0564_2a90076939024c358f477da838d85268.pdf JohnK

I think the answer is “maybe.” You’ll have to measure the requisite 300 mm spindle-to-pivot distance to gauge where that falls on the plinth, and if there’s enough room/plinth at that point to mount the VTA tower.

As to how easy, it depends on your level of experience. The s-p distance for the 9 is 223 mm, for the 10.5 258. "Spindle" in this case is the platter spindle, "pivot" is the tip of the spike the tonearm rests on. To install the 10.5 you have to remove the base, move it so that the s-p is 258, then mark, drill, and tap new holes for the base. JohnK

Either will work with the HW-19. JohnK

Yes, you would need to move the base to achieve the longer spindle-to-pivot distance of the 10.5. JohnK

If there's no hum when the cartridge isn't on the LP, then in my experience this is usually motor vibration transmitted via the belt. JohnK

That can happen if you, say, drop the platter against something that hits the spindle.

For tonearm length, rather than first setting the Feickert to 300, instead leave the measuring arm loose, set the pin on the top of the tonearm bearing pivot, and see what the measurement shows on the Feickert. The tonearm could be mounted at an incorrect distance, or it could be one of the not-quite-12-inch arms used for the HW-40, which are a few MMs shorter than the standard 12-inch. JohnK

I have seen that before. Did that come from the factory or a dealer? In either case they should make it right. JohnK

First, what's going on with the side of the plinth? Looks like the finish is delaminating, what's up with that? It is not unheard of that under adverse conditions the headshell can warp. I had that issue on a 12" 3D, which affected how the cart aligned. The issue you're having, along with the plinth, could indicate that something has affected the tonearm. Do you know the full history of the turntable? JohnK

If you really want to go at it, Mother's Billet Polish will clean everything up nice and shiny. JohnK

I think the comment about the arm length will fix it, but I note that I have used three Soundsmith carts (MIMC Star, Voice, Paua) on a 12-inch Fatboy with no issues.

Did you also check the clearance between the underside of the tonearm and the lifting pad?

Good luck. When I was looking for a set I even Bugged Harry to see if he had a spare set hidden away in his workshop, but no dice.