@Jonathan @lasertechs - Im afraid i slightly melted the lens holder this morning - I had cleaned the lens and put it back in, but the ‘lock’ was counterclockwise instead of clockwise, so even though it felt like it was locked - it was the opposite way.
The laser is still working, but could you possibly print us another holder, as it may not last for very long.
Sorry and thank you! It might be worth noting somewhere, (to check the lens is in) as it feels like its locked when it isn’t.