I'm smoking 6 racks of ribs in my 3D right now. 2 hours in. I can not get the temp past 260 and I have it on 275. When I put the ribs in earlier the wood ignited and caught on fire when I opened the door. I took it out and replaced the wood, put the ribs back on, and no fire since. What is wrong? Why will the temp not get up to 275? When I cooked 2 racks in it the other day there was no problem. It had 2 hours to get to 275 and never made it that high. Is something broke or what's going on? Any help ASAP would be great! Thanks.