When you say regularly fed, what do you mean? You should probably NOT be fertilizing cycads until they are well established and growing great, possibly on their 3rd or 4th healthy leaf.

Sounds like there is not enough moisture being pumped into the leaves by the root system, thus the dry edges. All the micholitzii types have a problem with aborting leaves before they are even hardened off. I have even seen this exact thing covered in a cycad watering article in a cycad website, so you are most likely experiencing this. I water my micholitzii types a little every day when they start to flush leaves. If you have good drainage, this shouldn't be a problem. All of these like a little more humidity and moisture compared to most other cycads. There was even an article in The Cycad Newsletter last year that showed where a man grew some debaoensis plants in a greenhouse that was getting watered 3 times a day, if you can imagine that, and he got some 8 year old plants to grow stems that were 24 inches to 32 inches in diameter.

Thank you for your replies. I will rethink the food and water. The odd thing is that the first leaves developed perfectly and still look great, just the 3rd leaf onwards start yellowing and drying before they are fully out.

No, that's exactly the way it works. Once the leaves harden up, they are good. The problem is when the leaves ate still soft. They just seem to need more water than other cycads when the new leaves are coming out. Once you have new leaves that harden up, you can go back to regular watering if you want. They still hold their leaves better over time with more than average watering. An indication of this would be that if you have an old leaf that just about dies back around the time the new leaf starts to appear, more watering could give you where you are holding two or the leaves that look good when the new one comes out.