I thought you had never heard of that problem with Mits.
You never clearly stated what your problem was, just the defect and the part needed... that has been fixed by tying this thread to Sheldons...
Don't you think Mits should replace these TVs after they have the same problem repeated since the light engine is probably only a symptom of a greate problem? Or do they just want a bunch of angry and disappointed customers?
I am not here to validate your feelings or what actions you think should be taken. I am here to offer understanding, education and possibly solutions you may have not thought of.
It that light there are state lemon laws, contact your state consumer affairs, and with extended warranties lemon clauses. For extended warranty these are typically triggered after three repairs within a certain time period. Check your contract if you have one.
Another solution: This customer for XYZ brand had a part replaced under warranty months earlier and they were on back order then, he had the same problem again still under warranty, needed that same part and it was on back order yet again. He contacted the retailer and had the product exchanged.
One thing you can count on is manufacturers who want to stay around don't make junk - they can't afford it. It eats up the service budget, clogs the phone lines and sucks up admin time like crazy. I guarantee there are folks at Mitsubishi just as upset as you are over all this! None the less there is little they can do except get it corrected, get the part orders filled and that is simply going to take time. Also, I have seen manufacturer defects, I mean real defects, oops, we (the complex collective of any manufacturer) screwed up here big time, and this is not one of those. Most sold are holding up believe it or not, unfortunately yours was not one of them.
For clarity, the expedite Sheldon speaks of is far more likely about 1st or 2nd day air shipping rather than a way to get your part shipped sooner.