I bought a new chain and sprocket.

Seemed like a good idea at the time, and eBay is always just a click away…

Turns out, the nice shiny new chain was a bit wider than the old one. All the high-spec roller bearings and such like added a few millimetres here and there. So although it fit in a theoretical sort of fashion, I was left with only one option to make it fit in a way that allowed the chain to actually move – cut away half the gearbox casing.

So, the chain goes back in the box, and I revert to making the old parts as “new again” as possible.

This was just plain tedious. First, wirebrush all the mess off the sprockets, so they look all shiny. Then soak the chain in a bath of kerosene for a day or so.
It comes out looking like nothing has changed.
Sigh.
So you get the wirebrush out again, and scrub off the rust and gunk. Then you cover the chain in oil and grease. rummage it around for a while, and put all the bits back where they belong.
Twitch the tensioners on the axle until the chain freeplay is about a half inch or so. Tighten the nuts and bolts, and apply the cotter pins etc.

Next time I’ll take measurements before buying replacement parts.

Maybe.