Arc-products.com in San-Diego, CA is your best bet to get help with Diagnosis. ask for Eddie. the whistle or whatever you call it is normal for Powcon machines. there is a couple threads related to that around here somewhere. Great machines, I have had 1/2 a dozen of them. most I fixed up and sold. Problem is that the parts are so expensive and usually only sold by the entire board that its usually cheaper to pick up a replacement of Ebay or Craigslist etc. Arc-Products is not doing as many repairs as they used to but if they can point you in the right direction you may be able to find a local repair shop that can take a look at fixing it