how to re-seal a vc defiant knock off?

re installed an old vc defiant knock off after its been in the barn for a few years. fired it up with a small load and noticed in the dark i could see the fire on the bottom in a few spots and the sealant fell off the top where where the top meets the middle section. should i take the 4 nuts off the top and pull the stove down and re-seal from the inside or use the rutland hi-temp stove cement to seal it up from the outside?

the stove looks just like a defiant but its definatly a knock off. any advise appricated! getting cold here.