Clean it as best you can and re-season. I got a used 48 too. All sorts of crap on the grates. Oven cleaner, scraping and wire wheel to get them to my specs. Re-seasoned using Flax Seed Oil. On first cook the thing would just not get hot. Vents fully open and with the door cracked, would not get above 275° or so. Somethings wrong here! Looked down the stack, which is a 4" diameter pipe, and there was but a 1" clear hole. The rest was clogged with greasy creosote so the cooker could not breathe! Scraped it all out, over a pound of gook from an 18" pipe, and now it runs like new. Just a heads up for you, the previous owner may not have known how to keep a clean fire in yours like what happened to mine. Have Fun!