So I recently bought a used forge setup that worked great for a short amount of time. I'm having an issue where shortly after firing up the forge I get a gargling noise that I've labeled as "backfiring" from the burner(s). I've surfed many youtube videos and forum posts looking for people with similar issues. I found quite a few fixes for the problem but after trying them myself I haven't been able to resolve this thing. I've really enjoyed my time learning the process thus far, and am hoping to get into knife making ASAP, however, I'm stuck on the side of the road here with this problem. The forge doesn't get nearly hot enough while this is happening and I've run out of patience with troubleshooting it myself so here we are. I'm gonna leave a list of attempted solutions below, and if anyone has any insight please help me out here.

* Messed with airflow/gas intake mixture via the intake regulators on both the propane tank and the plastic coverings on the burners. 
* Tried new propane tanks.
* Positioned fire brick on both the front/back sides of the forge in just about every position imaginable. 
* Adjusted the position of the burners in relation to the refractory coated lining. 
* Ran one and both burners at different times. 
* Threatened it with a hammer. 

Thanks!

Problems firing up the forge.