It looks like vintage VX derailleurs are going for 20-30USD on ebay at the moment, so it may end up making sense to just replace the whole unit.
Kurt Sperry Bellingham, Washington USA
2009/8/25 <kfhume@hotmail.com>:
> Hi,
>
> The helical spring that tensions the jockey wheel cage with the chain on my
> Suntour VX rear derailleur has broken. I understand that this company went
> out of business in the mid 90's but I wonder if its still possible to source
> spares for same ?
>
> Regards
>
> Ken Hume
> London, England