This sounds like a job for some aggressive young Congressional staffer (Imagine a headline saying "Congressman X gets Purple Heart awarded 90 years late!") It appears that he was considered by the Army to have been wounded (the wound accolade) and the VA accepted some proof to approve his grave marker's inscription. Those two facts should trump NPRC's or VA's inability to find records now. I'd bundle up copies of the accolade and photos of the grave, (plus copies of letters home mentioing the wound, or VA paperwork relating to medical care as a result of the wound, or whatever else you have) and documentation that you've tried to work through channels and send it all to your Congressman. He's got staffers whose jobs include doing that sort of constituent service. Or, see if your county has a Veterans Services Officer. These guys are usually retired military themselves and know people in the VA and NPRC system because they're always trying to find lost medical/service records for vets. After 10 years, there's no reason to go easy. Step up the effort and get real people involved on your side.