Stephen, (and anyone else with an interest)
I regularly shorten the muffs by gripping them in a minicraft drill and use a needle file to wear them down, at the same time rounding off the 90 degree sharp edge to them. This ensures that in the unlikely event of the 'spring' riding up over the muff it is far more likely to return to it's proper place without any need for outside interference.
Hope this helps.
While at the Hawick Show I bought an 04 shunter from C&G £37.50. As there was no postage involved that's about as competitive a price as you can get.
YES it is in rail blue with wasp stripes. I'll post a result when I've 'finescaled' it