It's my untouched WB2.1 that I'm trying to boot to now and still no go. I'm starting to remember how much I hate the Guru screen.
I'm going to see if I can re-prep DH0 while the 2.04 ROM is installed and see what happens then, otherwise I'll reinstall KS1.3 and start from scratch with it, see if I can convince it to play nice.
Thanks for the offer, I bought a bunch of chips from a bloke in Germany and am just waiting for them to turn up so I can fit them. KS3.1, ECS Denise and Paula and a few others. Also a couple of spare KS2.04 ROMs, I'll try them also just to make sure it's not my ROM causing this.