So my tube has been going down the crapper, well, since it was manufactured in 2007. That's what tubes do --- tungsten anodes wear out, maybe the oil starts to foul, high voltage arcing events add up. The anode is the thing that 100% sure "wears" --- it's essentially a light bulb filament, constantly boiling off electrons and at the same time growing ever more and more thin. It is a testament to the build quality of the PXS unit that it even still works at all. 

Earlier, I had turned down an offer to which trimpot to adjust to increase the heating/ brightness, after all since the thing worked at all and a dim x-ray source is better than none, and this might accelerate its demise. That demise was defined by, 15-20? microamps at voltage when I got it, and recently, barely 6 or 7. Very long exposure times...

And it got to the point that I was raising the voltage just to get that extra bit of punching power, and a couple extra microamps. (For reference, medical x-rays are measured in Milliamps.) And then after a particularly long scan failed, I popped up the voltage again and experienced my first big arcing event! 

The lights turned on and off and the current spiked to at least 200 microamps --- and you could hear something happening. Damn! X-rays came out as a trickle, barely illuminating the image, even with the current so high. Damn, damn, damn, that's it I guess.

Until on a whim I tried unplugging it and plugging it back in. And turned it on to voltage, no current, it held. Nice... and then 60 kv, "20" microamps... and it got to 20. 

70kv held. Produced real X-rays. much brighter than before! I just ran a scan at 70kv, and the thing held, rising from 26-29 overnight and running for 24 straight hours. It's definitely not just leakage, either; I've had to adjust my exposure times to be much shorter, with the added benefit I can now use more image averaging. Last scan was bin 2, 25 microns, 2500 images (200 degrees rotation) and 8x image averaging. By far the longest scan I've done, and hopefully, the data will be good and you'll get to see what it is.