In fact the oldest microlight at Masterton was the Kolb Twinstar II ZK-FVK, which was flown all the way from Christchurch. ZK-FVK was built by A McLean of Palmerston North and was first registered on 14/11/89. It has had 9 subsequent owners and is now owned by B W Thompson of Christchurch. It still looks exactly like it did when it first flew.
I remember ZK-FVK being built and completed at Feilding Aerodrome when I lived in Feilding in the late 1980's. There was another Kolb Twinstar built in the Manawatu area at the same time, being ZK-FVF which was later re-registered as ZK-JML and as such was involved in a fatal accident at Foxpine.