nice drag!
in thailand you should be able to find taiwan parts. if you go with the good brands like RPM, KOSO, RRGS, NCY you'll very good stuff for your transmission.
i suggest to install a good quality spring like the KOSO ones and install a spring slyder (like RDR one or if you can find the best is Pinasco) to reduce the rotation torque on the contrast spring.
anyway i think that to break a spring like that, or the spring is really bad quality or it's not the correct one for your transmission!