We've run into this before. I hope this helps:
By: CoaLen On: Sat Nov 08, 2008 4:07 pm
I had (have?) the same issue with my Koker. The sides of the "grate" don't go all the way back to the back wall of the furnace. There's about a 1/4" vertical gap. As the stoker bar pushes coal down the grate, some of the smaller pieces fall off to the side through this gap. It collects on the shelf below the stoker unit and once that area is filled, begins to collect on the floor of the furnace.
I cleaned all the ashes and coal off the grate and all the coal out of the hopper. I then cut a couple of pieces of rope gasket material to the proper length and pushed them into the gaps. This should prevent any coal from falling through, keeping it all in front of the pusher bar.
I'm assuming the gaps are simply a clearance designed into the furnace and stoker assembly to prevent any assembly problems. I checked mine very closely before doing anything, to make sure something couldn't be tightened to draw the stoker closer tinto the back of the furnace. Everything looked good, so I went ahead with my fix.
Here's the thread it's from:Members running a Keystoker DV