I agree with old sarge.
If you have nothing but ash, your wood has combusted and will lead to a bitter smoke. I use boats made from aluminum flashing and have very little ash. Mostly I have just charcoal left.
I don't see how the ash could be getting to the bottom of the smoker. I have had 7 smokers of the 3 name brands and none of them allowed anything to leave the wood box. Adding a couple of pictures of yours would help.