Wait, it is blowing all three ? Hmm, that stickies up the wicket now. That makes it more likely that you will have to go with the dual resistors in each place.

Much more likely, to the point where I wish I could edit the other post. That is now the most likely.

It might be alright to go with higher wattage resistors, it still has a fuse.

In this case the only other possibility is the transformer is putting out too much current and that, well, think you can win the lottery two weeks consecutively in a row ? (playing only one number each time)