John:
The noise you hear is probably the diaphragm popping in and out as it tries to respond to sudden variations in pressure due to a faulty valve sticking, or seat falure. I would stop using the outfit immediately, and take it to a qualified O-A equipment repairman. (Most welding supply stores can put you in touch with an o-a repairman, or have one on staff). Predictably, they will tell you what you already know - that there are no replacement parts available, and they wouldn't repair it in any case. However, they may be able to supply you with a pair of reasonably priced name-brand refurbished regulators (Victor, Harris, Purox, Aire Liquide, etc.) that you can use with the rest of the outfit you mistakenly bought. (New regulators would probably cost more, purchased individually, than an entire outfit on sale.)
(I'm assuming that you have already eliminated other sources of problems such as sticking flashback arrestor or check valves, and have already been refused action by Harbor Freight).
Good luck!
John,
Expanding on North's good advice, some regulators are built for high flow rates. I forget even my address, so check to verify that the type2 regulator isn't built for less than 5psig delivery... I dont know the nomenclature- it may be a letter or number, and I am uncertain of teh pressure threshold, but it gives you something else to check before you lay out cash... (Smith, Victor or the others should have an on-line catalog with the data you need to verify your apparatus)
Let me highlight the check-valve issue... I have had similar problems and replacing the valve (or, for test purposes only, eliminating it) have solved the problem, particularly at low flow rates. It may be necesary to use a smaller tip with a proportionally larger flame.
Also, what is the name of the Chineese junk youre sailing on? Some are actually supported by American channels which might be found on the internet. Others are actually so good a copy of real brands that the parts are, according to some advertisements, interchangeable.