The chassis jig performed it's magic again and once cleaned up I was able to fit the Romford wheels. All 6 touch the surface of a flat thing, in my case I like to use the disk part of an old computer hard disk which is excellent. Solid 0-6-0 chassis are notoriously difficult to get spot on, often locos see-saw on the centre set of wheels. You can tell if this is happening once the model is running, the middle wheels will be dirtier than the outer ones. Many builders actually set this set slightly higher to avoid this.
The rods are laminated up from two parts. To help those who have compensated the locomotive, they are in two halves pivoting on the centre crank pin. This takes a little more effort and care than making them up as whole lengths but nothing beyond even my meagre skills.
While I'm testing, the rods are held in place using insulation stripped from bits of wire. It's slightly smaller than the crank pin and can be slid on and off as required. Eventually I'll replace these bits with the Romford washers and some solder but before then I suppose I ought to put the motor and gears in ! As it is, this assembly rolls and up down a track with the slightest push and no binding. And it looks nice and shiny too.