So I took this laptop apart almost a week ago and diagnosed/fixed up what I could. It was a long time coming, but better late than never. Still waiting on proper parts to arrive, which should arrive less than a week from now with any luck!
In the meantime, weirdness. The fan is getting replaced, but in meantime it's running a lot quieter. And yes, it is definitely running, and sometimes makes the horrid grinding... but much less often.
Even weirder, Windows has finally sensed that something is wrong! Occasionally it alerts me that there is a problem with my cooling fan, and I should immediately turn the computer off and seek service (ha). I have no idea what's triggering this, as the heat sinks beside the fan are running FAR cooler now than before.
This has an interesting effect, though: All 4 cores are being spun down to an *absurdly* low clockrate. As in, typing this post is very annoying, because there is an input delay of of close to a second per word (which cumulates predictably if I fill the input buffer). SOMEHOW, youtube still works, to some extent (it takes a while to buffer, and often fails saying an error has occurred).
What ought to surprise me, but doesn't, is that this low-clockrate mode exists but cannot be manually activated through Windows. Trust me, having played several classic games like Myst which absolutely max all available CPU, I would know... There's a "power saving mode" which helped but still always ran hot.
Well, whatever. In the meantime I'm experiencing a similar experience to dialup, purely due to Firefox's bloated resource usage and this decrepid, yet admirably stalwart, heap of silicon and plastic.
Ugh had to fix *SO* many typoes due to the input buffer simply not registering keypresses. What a mess. I have another computer but I love this one and never should have let it suffer so long without help.