Days later, I finally got the time and courage to press that "on" button again for the in-better-shape university scanner. It's been running for almost 2 hours now, and follows the following pattern:

12 kv ---> mid teens --- 20-25 or more sometimes --- a tiny pop --- back to 12. Record I saw, pretty early on, was a peak of 32kv (and I'm setting it to 40kv with no current). 

I want to say that the max voltage or average has been rising, but the general behavior here is pretty stable. The tube in question is thus: 

https://www.thermofisher.com/order/catalog/product/PXS5925RR

Now, I want to say that this behavior is expected --- or even good. The source has built on conditioning circuits to raise the voltage and drop back down if the current spikes unexpectedly. Which is exactly what I'm seeing here. At the peak voltages in the 20s of kvs, it will sometimes show a couple of microamps at the moment it drops back down.

The question is, whether this process is entirely healthy and removing contaminants from the oil --- or if the occasional popping sound, likely arcing, will actually increase contaminants and permanently damage the tube.

What you want to do is set it to a voltage that it can be stable at for a while, then raise it in small increments. The problem is that while the minimum rated voltage on the catalog is 20kv, and I've seen it get past that regularly, the min set voltage in the actual software is 40kv (max 90). Now, this is super duper duper low by my industrial CT experience standard, but in an ideal case I would go to 20 --- I just don't know how to.

I'm liable to just let it do its thing and run overnight, but this could be a crucial mistake. I could take a step back and figure out how to drive the source manually, and set it to that minimum of 20kv. 

Hmm, I say, as i continue to let it do its thing.