How to compensate for high altitude when baking bread in a bread machine?
This site claims that you should add some extra flour and liquids while reducing yeast and sugar, while increasing temperature and reducing time. I'm not sure that I accept their reasoning behind increasing the amount of liquids (supposedly to counteract dryer air), but at the same time increasing the amount of flour. 

You probably can't adjust either time or temperature in your bread maker, though.

A lot of their reasoning is based on the air being dryer at altitude, but I would have thought that the breadmaker would be sealed enough to maintain a humid enough atmosphere inside.

That is based on 3500ft above sea-level , but you're twice as high. At your altitude water boils at 92°C, which means that the bread will expand faster in the oven, but before setting properly. 

If you can't change any other parameters, I would try to reduce the amount of dough in each batch, to ensure that it heats through faster