The kiln needs to be switched over from natural gas to propane.
A quick trip to Ace Hardware was enough to solve a plumbing problem.
The old MR-750 Venturi gas burners were still in good shape... The primary air shutters were frozen with rust but were easily fixed.
The nozzles orifices were set up for natural gas. The one pictured on the lower right was what was in place. The propane are much smaller. It made a HUGE difference when we ran test a test burn. Getting an oxidation flame was pretty much impossible with the larger orifice. The smaller orifice gives a much broader range of reduction to oxidation.