I was given the Bodum Bistro as a gift with high expectations. After brewing, the coffee grounds are caked in the top of the unit and the entire top assembly has to be dismantled and cleaned. This happens with every pot. I read the directions and noted that you should use no more than 8 level scoops of coffee per brew which is not really strong enough for my taste but I tried it anyway. The unit did the same thing, just not as sever. Any tips?