Gas and Oil Home Heating Furnaces - Fan won't kick off

Sorry, posted this under air-conditioning by mistake...
Hi - if anyone can help me with this - I've got an old Gregory woodburning furnace, and when I went to fire it up this year, the draft wouldn't open and the fan wouldn't kick on. So I asked around and most thought it was one of the limits - there are two, one that's a 250 degree limit and has four wires going to it, and one that's a 350 degree limit and his two wires going to it, on the fan side. Gregory quit making the stove some years ago, and Honeywell quit making the part, bless their hearts, and it's been impossible to find a replacement. I finally found a 300 degree limit, and put that in - the stove worked for about five days, but now the fan won't quit running. Is the top limit out as well, or is it the ancient mercury thermostat?

There are many different fan controls that you can use there. Id say we need the wire schematic First to say just what you need.;)

What's a wire schematic? I've got a page that shows what wire goes to what, is that it? Sorry, I'm really new to this stuff...