Drat,
Changed all 12 Halogen lamps/bulbs to LED keeping the GU5.3 holders and transformers.
Then 1 of the 12 lights started flashing after 10mins use, tried another lamp/bulb still same. So it looks like this transformer does not like LED's, so it looks like I am having to replace the holders to GU10 and remove transformers as when/if they start to fail.
Changed all 12 Halogen lamps/bulbs to LED keeping the GU5.3 holders and transformers.
Then 1 of the 12 lights started flashing after 10mins use, tried another lamp/bulb still same. So it looks like this transformer does not like LED's, so it looks like I am having to replace the holders to GU10 and remove transformers as when/if they start to fail.