The Raspberry Pi controlling the Robotic Arm has been crashnig, every couple of days. I think I know why - it's the USB-to-serial converter. Those work fine for ordinary PCs, but not for Pis. I thought I found one that didn't crash, but it seems that it isn't entirely crash-proof.
So I've replaced the serial-controlled relay box, with a USB-controlled one. Hopefully, that will stop these annoying crashes.
And I'm working on a replacement for the Night Mail.