I have to say that's the first time I came across your name, too...

I'm sure I've got plenty of low-pF capacitors somewhere but lying on the bench was a strip of 47pF ones. Try sticking one in series with one of the existing crystal load capacitors to reduce it a bit. It works! The radio can talk to the others now. Happy offspring. /end

The radio chip is a BK4819 and a data sheet is available. It says the master 26MHz crystal should be accurate to 2.5ppm, which is pretty ambitious for a toy. The example circuit diagram shows a trimmer on one leg of the crystal but that's not present in this radio. /4

A check with the spectrum analyzer confirms this. The faulty one is about 10kHz low on each channel compared with the others. Doesn't sound like much at 446MHz but it matters for narrowband FM. /3

Inside is this board. Neat, but there's not much to see and nothing to adjust. I had a feeling the radio was off frequency because it would sort of make contact when set to a different channel to the other set. /2

I think I bought that version of Red Hat in a big box from a real bookshop, when they used to sell such things. It ran on a Pentium 75 box, I think, under my stairs with a net booted 486 as an X terminal on the living room TV.

Put it back together with nearly all the screws and it still works. Job done. /end

Add a bit of Kapton tape to try and prevent a recurrence of the fault. It's pretty certain to get dropped again! /7

Yay! It works. Son will be happy. /6

Add a bodge wire to the other side of the via through the convenient hole in the board. /5

Looks like a bit of damage to this via connected to pin 6 (CLK) of the serial Flash chip which presumably holds the firmware. That's going to cause problems. /4

Looking at the construction closely, the pins of the printer motor come awfully close to the board just here (shown with the printer mechanism lifted a bit). /3

It comes apart nice and easily with a few screws, and is quite neatly made inside. There's a main PCB with the camera, printer and screen connected by FFC connectors. This one fell on to a hard floor and now does nothing except blink the display backlight briefly. /2

The permanent field magnet is cylindrical and hides inside the armature, making the motor slimmer. The whole thing is a marvel of precision, especially as it only costs a few pence. /end

The armature is entirely self-supporting, with no core at all. This makes it very light and able to spin at high speed, though I think the windings may be prone to damage. The commutator on this one is thoroughly worn out. /4

The brushes look pretty conventional. These motors are sold in CW and CCW directions, though in practice they work both ways. /3

A bit of Dremel action soon has the commutator end off and the armature removed. I think the outer casing is brass, not steel. /2

Link to the Stardot thread that started all this www.stardot.org.uk/forums/viewt... and kudos to @inufuto.bsky.social