Masterbuilt Gravity Series 560

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Original poster
Feb 26, 2023
We just purchased the Masterbuilt 560 and wonder why you can't purchase the top & lower charcoal door seal material anyplace? Seems like they (Masterbuilt) wants to sell you the whole door assy. Like to find essential spare parts for this as we live in the "outers" of the state... Thxs!
Yes I have been through all 78 pages... Could not find an 800 number to call.
Are you speaking about the seals on the top of the charcoal hopper and the firebox door ?

If so, LSS mods sells a hopper cover that works great for sealing the top of the hopper. This is the answer to the hopper leaking.

For the firebox door, Tom Horsman has done several mods to the 560, ya might search his vids. But I can tell you from experience, his mod for the top of the charcoal hopper does not work. He uses expensive tadpole gasket. The LSS hopper is the answer there.

But I think he uses the tadpole gasket on the firebox door. He may have a vid about it, IDK. And I've not attempted that mod.
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+1 to what Smokin Okie Smokin Okie said.

I have the LSS hopper cover and it solved my problems. If you don't want to order the full mod you can use lavalock around the seal for charcoal chute.

I haven't had any problems with the firebox door, but wouldn't doubt it if you did.

Have you tried tightening the nuts on the clamps at all? You can have them grip down a bit tighter, but don't overdo it or the doors will bow.
Thanks guys! Just seems "odd" that just the hopper cover & firebox door are not to be found. I am a millright by trade and all the "stainless work" is straight forward! If I knew the composition of the gasket material I could probably locate the source. Keep the thoughts coming I'm not the only person.
I've not had any problems with the firebox door , also. There's a leak in the upper left corner, but until that leak impacts the ability of the controller to keep a steady temp, which I don't foresee, I won't worry about it.

I'm still not sure what you're calling a gasket. Is it the rubber seal that fits around the outter edge of the hopper and firebox doors ?

On the hopper lid, and this is true of even the high dollar GF's, most people put a sheet of aluminum foil over the top. This helps the gasket seal and protects the lid from creosote buildup. But the LSS hopper cover eliminates that.

LSS gasket is just a felt gasket, its about 1" wide and its pretty thin. If you can work with stainless , you could make one very easily. I think there's a vid on LSS site showing the installation that gives ya good view.
Thanks guys! Just seems "odd" that just the hopper cover & firebox door are not to be found. I am a millright by trade and all the "stainless work" is straight forward! If I knew the composition of the gasket material I could probably locate the source. Keep the thoughts coming I'm not the only person.

There are two main types of gasket material on the MB Gravity Series. The first is the rubbery-ish (I am sure it's some type of synthetic) material around the hopper lid and firebox doors.

The second is a fibrous material (e.g. high temp fiberglass or something similar) for the two gaskets in the hopper chute and firebox assembly. I had to replace these on my as I damaged them when installing a firebox mod. The first pic below is a progress pic of when I was replacing the gasket between the firebox and ash bin. This will not be relevant to many people, I only had to replace them on mine because I damaged them.

The second pic is the LSS lid mod. It is a piece of stainless with gasket material on it. The gasket material is just lavalock or similar, there isn't anything proprietary about it.

I will say, the firebox door is one area I've not had issue with.

I found a parts list for the 560 here - it looks like they call what you're looking for the "Hopper Door Assembly" and "Hopper Lid Assembly", which looks to be this part and this part on the Masterbuilt website. I'd recommend verifying this with customer service before you purchase, but looks correct to me.

Firebox gasket:

Hopper lid with mod
Wow! Thank you for the post! Smoke on...
No problem at all. I've been down the rabbit hole on troubleshooting these things so I'm happy to help where I can. I strongly recommend you verify with customer service before ordering anything.

A similar parts list I referenced in my post had information on the 1050, and showed the gasket between the charcoal chute/firebox being the same part number as the gasket between the firebox/ash bin, so I ordered two of the same part. Turns out they are slightly different dimensions, and different enough so the listed part does not work between the charcoal chute/firebox.
A couple years ago when Tom Horsman was trying to improve the gaskets on the MBGF, he put the red tadpole gasket on both the hopper cover and firebox door. I've noticed in later videos, he's gone to the LSS mod on the hopper cover, but best I can tell, he still has the red tadpole gasket on the firebox door.

When time comes to tend to the firebox door, which I hope doesn't happen, I'll investigate the tadpole gasket. Primarily, because I still have several feet of that gasket from trying to do what Tom did. I got mad at Tom over that, because it did not work and he never made another mention of that. It leaked badly on the corners. is reader supported and as an Amazon Associate, we may earn commissions from qualifying purchases.