Ian, Hi. Member davknigh posted a similar question and answer over on RMWeb – I tried to include a link, but my message wouldn’t “post”, so I’ve copied and pasted his helpful text below. Good luck.
“Problem sorted. I took some advice from the Scalefour Forum that got me pointed in the right direction. Basically the best starting point is the inboard end of the bogie, I pared back the lugs a bit in the middle so as to get a starting point to wedge in the tip of a scriber and with careful levering the bogie side frame popped off.”