Some kind of beetle. Inquire locally for control recommendations - noting that beetles chew so if this "dying" you are seeing is more than chewed portions perhaps there is something else going on.

Most Cycads are pollinated by beetles which, although doing some damage, are usually not a significant problem. If you're on the east coast there is a butterfly, Theclinesthes onycha, which lays eggs on Cycads and the larvae can do significant damage. If you see small blue butterflies hanging around your plants that could be the culprit. Keep in mind though the group of butterflies often referred to as "Blues" (Lycaenidae) contain many species most of which don't affect Cycads, so watch for those that are active on your Cycads, not just generally in the garden.

Your plant looks like a Cycas thourasii but I had a similar looking problem with a small Cycas revoluta. A gardening place suggested it was scale but after drenching it with pesticide designed for scale there was no change, new leaves came up the same way. Later I worked out that during the wet season a lot of water drained past it and the ground remained fairly soggy. I diverted the water and since then the Cycad has taken off with no signs of the problem.

They're the only things I can think of that might help you on your way to find a solution, good luck with it.

Thanks mate, Im in Darwin, so that might explain it. It was happening before the last monsoon though and I haven’t had this problem in other big wets? I’ll go and ask the experts at a garden center when I get a chance.

I'm in Darwin too (actually Noonamah to be precise). We don't have that butterfly here, nor that Asian scale that's doing quite a bit of damage on the east coast. Beware though, some of the garden centres have sales staff rather than experts.

It is most likely a small caterpillar doing the damage(not sure of the name), they attack the new shoots as the leaves are forming and by the time the leaves open the damage is done. The only solution I have found to work is as soon as you notice new leaves forming in the center start to spray the plant with insecticide and continue every two weeks or sooner until the leaves are fully formed. They wont eat the older tougher leaves.