The next bit of the work was - on the face of it - simple: seating four tiny caps into the half-etched marks shown for them on the footplate. The etch provides five, just in case you lose one of them:
I tinned the backs of four of them with the usual 188 solder and Carr's Green Label flux:
However, separating each individual cap, filing off any excess tags, and positioning them is the very work of the Devil himself:
Eventually you get there:
...though if you use too much solder, you end up having to scrape all the excess off (as here).......which may take you longer than it did to position the caps in the first place.
With all four caps soldered in their correct positions, I could then add the front mounting 10BA nut. This is simply screwed tight in position using the matching 10BA bolt, brushed all around with flux, and soldered. The reason why it's screwed tight is to prevent solder leaking in towards the bolt and soldering that solid!
I test-fitted the smokebox shell, just to see where we were:
...and you can also see the curvature at the base of the smokebox front overlay. This is why you solder the front overlay at the top and upper sides, BUT NOT THE BOTTOM! As stated earlier, I used the handle of a needle file to form the curve, but you could also use a 3mm dia. drill bit. A useful point to note when forming the curve is to ensure that, when finished, the base of the overlay should sit perfectly on the footplate. If you can see a gap, your curve is too tight. Conversely, if the smokebox shell won't sit neatly on the footplate, it means your curve is too shallow.
This can be a difficult area to get right, and photographs of 171 and her sisters don't always show the curvature clearly.
I moved on to solder the preformed firebox and boiler barrel together:
....and since all the soldering is on the inside, with luck you should end up with a flush joint on the outside: