Am completely new to the forums, but I'm a keen cyclist and own several bikes but i now commute with Dahon Curve D3, which i believe is 2008 model. It was bought new from CH White, but had never been ridden when I bought off my cousin last year. I ride about an hour a day right through central London, and whilst the bike does take a bit of a battering on the roads, I'm very careful with it and have maintained it well over the last year, with regular servicing at local indie bike shops, as I'm completely new to foldies.
Unfortunately, over the last month I've noticed a massive deterioration in the bike, I've got an awful creaking coming from, what i believe, is the seatpost and a worse one from the hinge where the fold occurs. I'm also having serious issues with the front handlebar hinge - again the bit that folds. Where the lever is (sorry for all the non techy terms) it's continually coming loose and the stem very quickly starts to feel like it's coming off, after a few rides.
Could anyone advise me on what may be the issues, the bike shops have done the usual tightening of parts and making sure they are greased but nothing fixes them and they aren't foldie specialists. Any tips would be very much appreciated, as i'm not the original owner i don't have any warranty, and it's technically too old anyway, i'd imagine.