Merri, There is some useful discussion of Cycads (which is what a "sago palm" is) on a UBC Botanical Garden Forum -- see link below. Also, a photo would help, as I don't quite understand your description. PS. As you probably already know, Cycads are not palms at all -- they are a very ancient group of conifer plants. Also, being of tropical origin, they tend not to follow annual growing cycles, but rather grow when conditions are favourable (sunshine, soil nutrients, water, etc.). Otherwise they go dormant, sometimes for a long time, looking like a lost cause.... Here is a link that might be useful: Cycad discussion example from UBC forum

My sago My Washingtonia Robusta

The new leaves are normally light green before they harden, sounds like they haven't developed in full yet, wait a few more weeks, and make sure you water regularly so the leaves fill in nicely. I doubt fertilizer at this point does anything as most of the energy and nutrition that goes into the new leaves comes from starch reserves in the stem. Fertilizing right after the flush has completed will help the next set of leaves.

I think you're a good plant person with the wrong information. Your problem is you believed what you read on the internet. Most of the information that I see appears to be from people who are just repeating the wrong information they heard from someone else that they thought knew what they were talking about. I have heard what is happening to you at least 200 times. (I get 5 to 10 emails every single day from people asking me cycad questions). Let me guess, your plants leaves start to turn yellow then they die. Then it goes up to the top of the plant and dies. Does that sound about right? If you look at the big wholesale nurseries down here in Florida who are growing 10 acres of Sagos, most of them are watering Their sagos every single day during the summer time and every other day the rest of the time. On top of that, we get 4 inch rains in an hour multiple times during the week sometimes. We get 12 inches plus of rain each week during the summer time and they're just fine and they don't rot. Good draining soil is very important but most cycads don't want to be dry. It is not the same thing. The good bagged mix of Canadian peat, perlite, and sand would work real well. They don't need Cactus mix or orchid mix. If I were you I would repot the plant, I would incorporate a time release fertilizer like Nutricote or Osmocote, and water it once a week while it has no leaves, and water it real good at least twice a week once it starts pushing new leaves. For more information here is a website written by a person who has tested what he talks about in his articles many times before it goes in print. I would really read the fertilizer, water and soil articles specifically. Good luck with your plant. With the right information you should do fine. http://cycadjungle.8m.com/cycadjungle/articles.html