Observed an ignition failure code today. Burners initially lit, however the flame rollout was so excessive that I recorded video and showed the business owner. The flame sensor had been rigged prior to our repair and further inspection found it was cracked. In good faith I did a thorough inspection of the unit and eventually it did fire up. I am having the business owner sign a waiver that we are not responsible for any hazards or damage that may occur from operating the unit. The rollout safety devices are working at this time, however the manifold is worn and older controls may not always function properly.