I got fed up of having to refill the lubricators on my Britannia every few laps, and risk them running dry, so I decided to increase their capacity. I bought a length of 3/4" square brass tube and soft-soldered a 2" length into a hole cut in the forward-facing side of the lubricator tank, with an end plate soldered on. The first of them looks like this after repainting:
The tank should be hardly visible under the running board.
When I soft-soldered the tank joint lots of little rollers fell out of the roller clutch pressed into the tank body, so it obviously has a plastic component - this hadn't occurred to me. I was able to buy a couple of replacements from Steamfittings and I managed to extract and replace the molten one.
This enlarged tank should provide ample capacity for an afternoon's running, if not a whole season. It also means that the tank doesn't have to be filled so full, and so should reduce the risk of oil getting onto the clutches and causing them to slip, which is an annoying problem that I encounter from time to time.
I just thought that this might be a useful improvement for others to consider.