"Ich würde da einmal drauf achten."
The English sentence seems a bit askew from the German, and the two English translations given seem not quite the same. Is there a better English translation?
Actually, "I would pay attention to that" seems fine from my point of view: If I was you, I would carefully pay attention to that the next time you run the washing machine. auf etwas achten is approximately paying attention, watching something with a sharp eye.
As christian already said, it's a modal. But I want to add, it's quite possible you can get a glimpse of it: 'einmal' adds a casual tone. More literally, it says: on occassion, sometime, eventually. Das solltest du auch einmal ausprobieren – You should try that, too, sometime.