How much space it too much, when lid warps. Will flipping lid help. My lid sets pretty well when cold, but develops a lot of space when firing. I know some space is ok, but mine looks abnormal, over 1/4" in places. Is there a high temp blanket that would help with this?
The center of the lid bows slightly inward toward the firing chamber at high temperatures. This is because the outside lid surface is cooler than the inside surface. The expansion of the lid causes a slight gap between the lid and kiln body but not enough to affect the firing.
If the hinge does not allow the lid to float freely, the front of the lid can rise 1/4" - 1/2", causing heat loss. Placing a weight on the front of the lid can add stress to the firebricks. Instead, adjust the hinge so the lid has play that will allow it to float when the firebricks expand.
The ceramicartsdaily.org forum recently published 450 spam posts. I agree with the suggestion that new members should be allowed to post online only after a moderator has approved their membership request. Yes, a spam script writer can come up with a statement that sounds like it was written by a potter. But a moderator can always see through it.
If it were my kiln, I would go ahead and fire to cone 6. You don't need to fire it empty unless you are not sure the kiln will reach cone 6. The small broken brick likely does not need maintenance. But you should fix the bulging element so that it doesn't get worse. The kiln should be at least 12" away from the nearest wall. So, you don't need to push the kiln farther away than it already is.