Fireplace repair, what gaskets to replace?

[farmguy69]

Hello all, new here.
I have a Vermont Casting winter warm system and I am currently replacing the cast iron side of the unit. I have removed the top and right side and in the process the left side is a little loose so do I need to go through and remove all the old gasket material? (its a caulking tube type) And by that I mean since I have broken the seal, remove both sides back and put all new sealant in or will things be tight after I reassemble?

Thanks

......I'm pretty sure of the answer.....I'm just confirming before I start...lol