Thanks, I’ve just googled a photo and I see how they go. It all becomes clear when someone point me in the right direction.
I managed to get the second idler post out today. I put as much pressure on it as I physically could with my 20T bottle Jack and it wouldn’t budge. I took 3 of the inner bracket bolts out in case they ovalised the bracket bore and then heated the bracket. It went with an almighty bang and I thought the Jack had exploded. It moved about a 1/4” but chunks of rust were thrown about 6’! Scared the crap out of me.