For reference, this is how the R50p panel looked before I took it apart. Note the differently-coloured backlight cable and the non-mangled foil tape. Yes, not only have I now taken apart two LCD panels, but I even managed to put one back together! With any luck, it'll even work.
To begin with I had to get the LCD panel out of the R50e's lid.
The inverter came out easily enough...
...and the panel followed.
Unfortunately, along with the panel came this little chunk of metal. It's never a good sign when you discover loose parts inside a laptop.
Even more unfortunately, it turned out that this was from one of the hinge brackets.
It's from the right-hand hinge which I was hoping to reuse. I think I can still do the hinge swap - it's the middle bracket that's broken off, and it's probably more important to have an intact hinge mounting. Anyway, with that done and the flex-pcb assembly removed I now have a second LCD panel waiting for the screwdriver!
Or not - turns out that on this panel the bracket was merely clipped in.
Normally letting the layers separate is a bad idea as dust can get in, but this is the sacrificial panel and so I wasn't overly concerned with keeping it intact. In fact, after some more prying and careful levering I'd extracted the entire reflector assembly. The metallic layer behind it is actually glass - probably a diffuser.
And there's the end of the CCFL tube itself. This is so much easier when you can take a destructive approach.
To get it out, I carefully bent the metal bracket down (which it later turned out wasn't physically blocking the tube - it was a loose L-shaped piece). The white reflector lost an argument with a pair of scissors when I found that it was stuck down in the middle, and after unpeeling the remains of that the tube just slid out perpendicular to the metal bracket. And with both connections intact!
Here's the two CCFL tubes side-by-side. The top one is the donor tube from the R50e, the bottom is the failing tube from the R50p (with the disconnected end taped over). Most importantly, while the donor tube is slightly smaller diameter they're both the same length and the cable mounting is close enough to fit!
Fitting the tube into the R50p panel had a couple of moments where I was very worried about the amount of force being applied - I don't know what it'd take to break one of these tubes, and I didn't want to find out so I treated it very gingerly - but I managed to slide it into the reflector without, I believe, damaging the cables. The panel then went back together quickly enough after the obligatory "where does this bit go? Oh, under that one I've fitted" moment, and it's now ready to be fitted back to the laptop.
I've yet to try powering it up - I need to put the flex-PCB assembly back on it, but once that's in place and the inverter reconnected (I'll use the R50e's one, to match the tube) I can probably do a test powerup before fully reassembling the laptop.