RV Repair: hot water tank bad flame, hot water tank, hot water heater

Question
Hi, and thanks for being here. I just bought a used (1999) travel trailer. A gas line inspection was done and the RV shop said the tank lines and regulator were clogged and replaced them. The problem is that the (DSI) hot water heater flame isn't consistent: it flutters and "woofs". I tried adjusting the air mixture collar but it just got worse. Sometimes the flame seems OK for 10 seconds, and then it gets bad again. I checked the air/gas tube for debris and it was clean. I checked the gas valve pinhole for debris and it was clean. I tried running on the other gas tank and there's no change (I think they're both over half full). The gas range is the last fixture on the gas line and the flame on all burners is nice and blue and solid. Is there gunk in the HWT gas line? Is the gas valve defective? Is this something I can fix myself? Thanks in advance!

Answer
Most often spider webs create that problem. I like to fray a piece of stranded wire and ream out the burner assembly.
I have also found on the atwood heater the regulator bracket and the burner tube are not in a straight line causing back burn and fluters. good luck.jim