I acquired an OBVIOUSLY older dahon, but not only do I not know what model it is(or build year), but I need help with the brakes. Attached to this post(or in reply to it), you will find pics of both the bike and the brakes(sorry about the quality, I can't find my Real Camera).

Anyway, the brakes are a belt putting resistance on a drum, but they keep loosening up on me. Last week I was going down a hill and had to use my shoe for brakes half way down. Anyone here know what vintage this bike might be or know much about this brake system? Local LBS owner and I will(at some point) take the wheel off and attempt to determine the issue, but I thought I'd put out a request here too.

Any help would be appreciated. Thanks!