Hell's Bells!
Somebody else actually owns a Number2 Mark2 Burner?
I thought I was the only one left.
I used to repair those little beauties in a previous life, and salvaged enough spare parts from the scrap box to knock one up from scratch.
Best thing to lube the leather with is vaseline. Works pretty good on the rubber, too. Needs replacing regularly, naturally, as the petrol washes it off. Especially on the non-return valve.
Getting a roaring flame out of it takes time- It's not like a coleman. All that brass needs warming up.
Make sure the priming bowl is at the bottom of the burner- it's easy to assemble it immediately under the burner head- it's no good there. Troops used to do that all the time.
Pump it up a good few times, and let fuel fill the priming bowl. Shut the valves.
Light the head up and ( this is the important bit ) leave it alone until the fuel in the bowl is nearly out. Then open the valve.
Then pump like billy-o. As long as your pinhole is clear, the only thing between you and the roar is the pressure in the tank.
I've had mine for 15 years, and it wasn't lit for a stretch of ten years at one point. Bit of TLC and it brewed up first time.
Bombproof, I believe is the term. ( They have to be if they give them to the Cavalry!)