If it is a Kelvin Hughes radio then it is a Husun - not Hudson. Unfortunately the link above is for a Raymarine radio from a seller called Hudson. Although obsolete, this model had a good reputation and a cheap repair would probbaly be worthwhile. Perhaps someone will come along with a manual - I couldn't find one on t'internet.
Although a great radio in their day, I had one too!!
Unless you can find someone to take it on for the cost of a few beers, any commercial outfit will probably end up charging close to the cost of a modern replacement with no real guarantee of a long term fix.
It might just be the time to bite the bullet and buy a nice new DSC set.