http://airsoftcanada.com/showthread....ghlight=DE+mag
I had the exact same problem, which was fixed the same way.

I disassembled the magazine, cleaned and wiped down all the parts, re-sprayed on a decent amount of silicone, and when I put it back together it worked fine.
Other than that, yeah, you might have to get new seals for it. But there's a good chance reassembling it will work.