Shaking your stove takes some practise to get good at it. With the Harman shaker system, you can easily pull or push the shaker grates to far which will allow large chunks to possibly get jammed in the shaker grates. (Harman allows alot of travel in the shaker grates to make dumping & cleaning out much easier) Unfortunately, this labor saving shaker mechanism can also get you into trouble if you are just trying to shake down a good fire. Only practise with it will do the trick. You will find that short, choppy movements will work better than longer ones & taking your time is always a good idea. Whenever I try to rush things is when I have "jamming" problems. Good luck!