Cumberland MF3800 rope gasket sizes?

[rodneygt]

My cumberland stove has a gasket on the window, door and ash door. In the last few weeks, I've gotten low vacuum cut offs on two occasions when I was running the stove hot. It will relight if I let it cool down but if I try to relight it hot, it will try for a bit and then cut off with the low vacuum warning again. I've noticed over the last couple of years the rope around the window has been disintegrating.

Does anyone know the correct diameter rope?

The originals are deformed from closing the door, etc so its hard to tell. Lowes has rope gasket kits in 5/8 and 3/8. I can always buy some of each and take the ones I don't need back but would prefer not to.

I got this stove in the late fall of 2011 as a factory reconditioned model off of ebay, so the rope is at least that old.

Thanks

EDIT: Also, lowes here has white rope gasket. I've also seen black/dark grey rope (graphite). Does it matter which type you use?

 

[Bioburner]

Type of gasket dose not matter but I have found the graphited rope seems to keep its shape better longer. There is also 1/2 inch in the size selection. One can if it is slightly bigger than OEM pull it as applying and will decrease the diameter. Couple of Harman users have found that to be a better choice than the OEM 3/8.