I did purchase the Engineers Emporium grate which is a great improvement. The engine is now running well although still a wet engine. It draws at lot of water through the cylinders when running.
Have worked out it needs a big fire - I fill the firebox with as much coal as possible and let it burn through while on move. I can leave the axle pump on all the time to keep water between 1/4 and 1/2 glass, anymore and the loco primes badly.
I fitted a Bruce Engineering lubricator or RH side of engine driven off the valve rod. Much easier to get at. Also I removed the oil check valves from the steam pipes and fitted one between the lubricator and the tee where the oil pipes split to feed the cylinders. So now both cylinders get oil not just the side with the weakest check valve - path of least resistance!