I actually had this same issue with my 6 D Cell mag last month. It turns out most of the battery companies will give you a refund if you sent in the broken flashlight with the stuck batteries. (If the batteries have not gone past their expiration date)

So I sent mine to Rayovac and got 6 new D cells and a check for $33.

I've also read on other forums that Maglight has an agreement with the battery companies so you can send it to them as well, but that's just word of mouth and I would contact mag to double check.

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1983 Benz 240D - 263,060 (Current)
1983 Cadillac DeVille - 130,000 (Scrapped - Stupid HT4100)
1992 Dodge B350 - 150,000 (Sold)
1984 Mazda 626 - 299,997 (Scrapped)