Welcome to the site. I actually visited the Northern Island of New Zealand way back in the late 90s, my sister went to both islands. Both of us agree that your country is just GORGEOUS and the people were very nice everywhere we went. Some of the people I've worked with do a month every year there too for polar runs down to Antarctica and they all love it too.
Anyway, the tops on the mid 90s cars very often need replacing at this age. Yours might not but it might... good news is that there are plenty of replacement tops available for not too much $$$. I'm sure shipping internationally would not exactly be cheap but I know that sending a part by sea is not too bad if you can wait a month...
If you don't think you need a new top, you can for sure adjust what you have. Here are the installation instructions for a new top, maybe you can see something in there in the adjustment section you could use?
I'd honestly see about replacing the entire top though if that's something you think you can do. Or you can see what a shop would charge you to do it. The part itself is $175 USD plus whatever shipping to NZ would be.
Hope this was somewhat informative...