Picked up a used SCF 050 Sunday for my pole barn and am in the process of cleaning it up. I noticed that it is missing two of the cleanout covers, the one behind the ash pan and one next to the burn pot. I have a real dumb question; how do these covers fit? There seems to be screw holes on the ones next to the burn pot but nothing for the one behind the ash pan. Are these covers supposed to be tight or are they a little loose? I have found replacements but is it that critical that they be original - couldn't a piece of flat steel screwed in place be OK?