Accessing The Fan: How To? Ease Of? The Fan Has Stopped Working.

How would I go about accessing the fan safely?Instructions or suggestions - or your own diagnosis and solution of the problem - would be greatly appreciated.Details of problem & inquiry:*For the second time, the HD DVR overheated. The first time, I caught it early. turned it off, let it cool down, and then I blew the dust out as best I could through the side vents with a compressor. It worked great for a couple of weeks. Now, the second time, I did not catch the machine overheating soon enough, I think. Again, I turned it off, let it cool down, unplugged it, blew it out with the compressor, turned it on. While running the startup program, it got stuck. Powered off ad on. Got stuck in same place. I pressed the reset button. The startup looked successful, yet it was running some self-diagnostic tests. It was then that I located the battery of manual equipment tests. I ran each one. The machine passed all with flying colors - except for the fan. I turned it off, unplugged it, and now I am talking to you, *The "easy" Solution" The easy solution would be to call customer service and take advantage of the free whole-home upgrade I am eligible for, right? Not really. My home is under renovation at this time, thus the reason of the inordinate amount of dust being kicked up daily - the dust which I believe is the probable cause of the DVR overheating. I feel upgrading to new equipment at this time while renovating would be a bad idea. Do you agree?. I would appreciate any advice, ideas, instructions - or your educated diagnosis or solutions - about how to get the fan to respond if it is not seized, safely.Thank you for your time and consideration! V.S.