I'll Keep That.
When I said that I'd thrown away the diode from the light switch, what I meant was that I'd put it in the come-in-handy electrics tray - one of my more propitious decisions.
With the magnetiser complete, it was time for further tests. We noticed after each operation of the momentary switch, it sounded like there was some sort of fizzing going on which lasted for about a second once the button was released.
Half-jokingly, I suggested that we might need a diode in the circuit and to my surprise, that was precisely what was required - though where in the circuit it would go was beyond my pay grade. With the aid of a diagram, Awkward explained to dopey how a diode worked and...
... amended the master wiring diagram. The diode (a mains compatible example) was retrieved and added to the circuit. More testing indicated the successful elimination of the worrisome sizzle. So, all's well that ends well and my thanks to Awkward for the wire and wiring, and John at Blue Swallow Aircraft for sending over pictures of his own magnetisers and a magazine article that I couldn't access.
When I collected the radiator after it had been recored, I was instructed not to use the plastic zippy things to attach the electric fan - I had to think of something else. This was a bit of a facer and I'd been putting off tackling it for some months. I had a bag of miscellaneous fittings, four of which had threads in them. I made up a thin steel ring and happily, got all the bolt holes in exactly the right places. I noticed then that I had to remove part of the copper overflow tube and replace it with a section of flexible tubing to accommodate the curve of the ring.
With some rubber edging fitted to protect the fins of the radiator from the ring, I then set about making the cardboard pattern for the brackets.
The bends were quite complex, but I persevered and eventually got what I wanted.
The fan mounting ring is bolted to the radiator mounts. There's a little bit of flex at the top of the ring which I'll have to eliminate with an extra something - a tie-wrap or some such.
With that job out of the way and the fan wiring able to be routed with the temperature sensor and water pump gubbins, I have no excuses left for not keeping up with the programme.