To avoid getting coffee grind in it, we tend to use somewhat courser grinds when making mocha. Recently there was a study that adding a tiny splash of water prior to grinding unlocks the most flavour, so there’s that as well.
We are still not sure if it is better to slowly heat it from cold water or to just put it on the hottest and have it done faster. As I was typing this, I did a quick search and some guy on reddit even has the water boiling first, before assembling it. I suppose it doesn’t matter all that much, as long as the grind size is not too small.
That being said, I’m hardly an expert, but I do enjoy a good mocha coffee from time to time (I think I will have one now, actually).