I used to have the perfect recipe for bread in my bread maker, with a flour I can't get any more. I now use whichever seedy bread flour I can get hold of and the same recipe but it always comes out heavy.
What do I need to do to fix it? Less water? More/less yeast?
At this time of year I put warm water in rather than water straight from the tap. Just a few degrees difference in temperature makes the bread rise much better, tap water makes a flat hard loaf in the winter. I initially blamed a change in flour before I realised it was a change in the weather!