I have an old second (third? fourth?!) hand kiln that should be able to reach up to 1300 degrees but seems to be getting stuck at around 200 degrees less than I need. I managed to do a bisque firing but when trying to do a glaze firing the kiln stopped at 1075 degrees celsius and then started to cool whilst still on. The controller (Ipco 3300) showed 'END' even though it had not reached the temperature I wanted and did not show an error message. I have no idea about the history of the kiln, when the elements were last changed etc etc.
I (think I've) checked the controller settings to make sure nothing is set to hinder the maximum temperature. I have read about working out if it is the relays or the elements? I am a total rookie so don't really know where to start. Is this the best first move to troubleshoot the issue? Or could it be something simpler?