Took the trike for a shakedown ride in the gap between sleet flurries, after months of neglect (barakta having been having too much trouble with her vision for winter cycling to appeal[1]). The electrickery worked properly, which was reassuring, as it was last used in a monsoon. Brakes were a bit underwhelming, but came back to a useable level with repeated hard stops. Evil rattle from hell and minor rubbing from the general direction of the left mudguard, which needed some adjustment. A quick fiddle with the lighting confirmed loss of standlight functionality from the left Pixeo. On opening it up, the remaining supercap[2] had sheared its legs and was ratting free in the bottom of the light.
I was able to solder replacement legs to the stumps on the capacitor, and reattach it to the board, followed by copious amounts of hot glue by way of mechanical reinforcement. I then did the hot glue thing to the other Pixeo - which still has both its capacitors - and, while I was at it, the rear light from my Brompton, which is an even worse example of mechanical optimism applied to electronic components in a high-vibration environment.
Re-fitting the lights, I noted that there was still some rattle, and decided to amputate the damaged mud-flap (which was hanging by a thread after rough treatment in the back of a car at some point). That seemed to sort the worst of it out. I also tightened the mirror mounting a little, as it was suffering from droop.
I also replaced the PSU in the m0n0wall box with a modern high-efficiency one, as it had been running on an emergency backup ancient noisy thing from the compu-tqt collection. This actually involved a three-way rotation with the PSU in my desktop, on account of the new one lacking the splittable motherboard connector to retain compatibility with older motherboards. My power meter suggests that's lowered the steady-state consumption by about 20W, though the power factor is worse, so it's only better by about 12VA. Really should have got round to that sooner!
[1] It's not much fun riding with your head at headlamp height when it gets dark at 5pm.
[2] The first suffered a similar fate a couple of years ago, with failure of the spot-weld attaching the leg to the case. I just removed it and made do with half the standlight time - it being the nearside light.