Hobbyists skill required

The first kiln we have returned because of the fan circulating air somewhere touched the case. There was a noise as if the oven is falling apart.
Two days later came a replacement. Immediately tried the recirculation mode, all the best. Now, after several -gleiches operational problem.
With heat at some stretches a housing part and the fan makes again this terrible noise. Then I was again to Information Exchange and too stupid I've found the cause. The guard is too close to the fan !!! -Here Is probably tried anything !!
I have the protective cover bent a little, now is rest.
Too bad, because otherwise it's a good device.