Thank you for that. I've had a good look over and don't think there are any of those small bugs you mentioned.
I've posted a picture of the 'freshest looking marks.its like the start off as yellowing under the skin then turn scaly/woody.
I just assumed it was scale.
The cactus had been neglected by the previous owner.
I have 3 cuttings that I removed when I repotted it as the shape was a bit awkward.
I've put cinnamon on the cuts.
The new growths on one of the cuttings is showing the same marks.
