So re-checked. When I did the first post, lower PF GI wasn't working. Replaced fuses - then worked. Started game and noticed (after a little while) that the GI was out again. Checked fuses (out of the sockets) and all OK. Checked the fuse I replaced, and it was OK also (I simply replaced the fuse without checking).
So, it's not a fuse. But it is the purple / purple white GI on FUnhouse which if Fuse 106 (not 107) as I said above. That fuse is also OK.
Physical check of the lamp holders and all appear OK. First bulb in the chain doesn't light so it appears to be a full chain problem.
Is it likely an issue on the power board and I by chance moved something when I replaced the fuse?