Today I went to try some more cuts, and the cooling pump wasn’t pumping. Again it was because of a big bubble in the reservoir. I added more water, I think about 30ml. That was enough to get it going again. I suspect that all the air that was previously circulating around in tiny bubbles had gathered together overnight, rising up into the reservoir to make one large bubble too big for the pump to push through.

It looks like, when you’re first setting the Beambox up, the reservoir needs to be checked every day for excessive air.

Probably also when the laser tube is changed, too, I’m guessing.