Brushcutters

I have a new fx555 brush cutter that when started runs near wide open. Throttle has no affect. Took it to an authorized service center and they have had it 5 weeks and still are stumbling around trying to locate the problem for an estimate to repair. They reported the husqvarna representative has even weighed in on the problem but was no help. I think we all know it's sucking in air from somewhere but I'm a little dumbfounded that the service center cannot test for the leak. Air leaks are a simple thing to find on most any 2'cycles but not this one. Any ideas as to who in Georgia can do the necessary test(s) to locate the air leak?