The handlebar post on my folder was not a tight fit anymore and was moving about as I cycled, not a good thing. The clamp that secures it in place was loose and would not respond to any adjustment. The bike was bought second hand and the previous owner had replaced the original one on which you could adjust the height of the handlebars making it more versatile. Luckily I managed to find an original modified Dahon replacement on eBay sold by a dealers specialising in folding bikes.
A cycling blogger Annie is also a Dahon fan so hopefully she finds this useful.