I've been lurking here for some time and finally have something useful to contribute. I have a 2003 Harman Accentra, meaning it has the feed auger chain drive. I'm the original owner.
Recently I started hearing a loud clunk while the auger was turning so I took the back off to watch it. The clunk was actually happening *twice* every auger revolution. Turns out the movement of the feeder slide plate was being restricted on both opening and closing. I discovered on this site that the slide plate access compartment can become filled with saw dust (i.e. "fines"). Sure enough I opened up the compartment and it was packed full:
![[Hearth.com] Yet another Harman clunking diagnosis](https://www.hearth.com/talk/attachments/slide_plate_chamber-webp.306618/ "[Hearth.com] Yet another Harman clunking diagnosis")
You can see the slide plate at the top edge-on. The black thing just below the plate is the paddle that pulls/pushes the slide plate open and closed. While packed with sawdust the black paddle can hardly move at all. So I vacuumed it out and thought I'd solved the problem. I restarted the stove and at first it ran fine but after a while the clunk returned, only it was *once* per auger revolution instead of twice!
After some more googling and poking around in the stove I found that the chamber below the slide plate and above the auger was filled to the top with pellets. In fact it was so full that the slide plate access compartment was full of pellets too. Next I thought maybe the auger motor is weak or slow. Once again I started the stove and watched the motor sprocket turn. It's supposed to be 4 RPM and sure enough it was turning 4 times every minute like clockwork under load (i.e. turning the auger).
The only thing I hadn't checked was the auger itself. It looked like a real PITA to remove but finally got it out and here's what it looked like:
![[Hearth.com] Yet another Harman clunking diagnosis](https://www.hearth.com/talk/attachments/auger_before-webp.306623/ "[Hearth.com] Yet another Harman clunking diagnosis")
I realized that the burn pot end didn't look right. So I looked up pictures on the internet of this exact part and sure enough the end of the flute on my auger was bent. Being a cheapskate I decided to bend the end of the flute back into shape (more or less) with pliers and try it out. Here's the result:
![[Hearth.com] Yet another Harman clunking diagnosis](https://www.hearth.com/talk/attachments/auger_after-webp.306624/ "[Hearth.com] Yet another Harman clunking diagnosis")
The stove now works correctly: no clunking at all and the flame is larger and hotter. In retrospect I had been noticing more clinker buildup and a smaller, cooler flame in addition to the clunking. Clearly that little bend in the flute was causing pellets to pile up at the entrance to the auger and interfering with the slide plate movement. In addition the amount of fuel delivered to the burn pot was being restricted.
Recently I started hearing a loud clunk while the auger was turning so I took the back off to watch it. The clunk was actually happening *twice* every auger revolution. Turns out the movement of the feeder slide plate was being restricted on both opening and closing. I discovered on this site that the slide plate access compartment can become filled with saw dust (i.e. "fines"). Sure enough I opened up the compartment and it was packed full:
You can see the slide plate at the top edge-on. The black thing just below the plate is the paddle that pulls/pushes the slide plate open and closed. While packed with sawdust the black paddle can hardly move at all. So I vacuumed it out and thought I'd solved the problem. I restarted the stove and at first it ran fine but after a while the clunk returned, only it was *once* per auger revolution instead of twice!
After some more googling and poking around in the stove I found that the chamber below the slide plate and above the auger was filled to the top with pellets. In fact it was so full that the slide plate access compartment was full of pellets too. Next I thought maybe the auger motor is weak or slow. Once again I started the stove and watched the motor sprocket turn. It's supposed to be 4 RPM and sure enough it was turning 4 times every minute like clockwork under load (i.e. turning the auger).
The only thing I hadn't checked was the auger itself. It looked like a real PITA to remove but finally got it out and here's what it looked like:
I realized that the burn pot end didn't look right. So I looked up pictures on the internet of this exact part and sure enough the end of the flute on my auger was bent. Being a cheapskate I decided to bend the end of the flute back into shape (more or less) with pliers and try it out. Here's the result:
The stove now works correctly: no clunking at all and the flame is larger and hotter. In retrospect I had been noticing more clinker buildup and a smaller, cooler flame in addition to the clunking. Clearly that little bend in the flute was causing pellets to pile up at the entrance to the auger and interfering with the slide plate movement. In addition the amount of fuel delivered to the burn pot was being restricted.
