H'm, I'm guessing that is a slightly older model. Dahon might have the parts, but might not. They stopped the "Helios" line a few years ago iirc.
The white one psyk is talking about is probably the 25th Anniversary Mu, just came out this year.
I'd contact Gaerlan, nice guys who deal with a lot of Dahons, Dahon upgrades, spare parts and so forth.