Nutrition/minerals if first suspect.

Apply some palm/sago fert.

Results in next set of fronds.

That is mechanical damage! Those leaflets are damaged by something. Look, the rest of the plant is perfectly green and the only damaged leaflets are on one side of the plant. Only the owner knows the answer to this question. Either there is wind, or something that has torn the plant apart on that one side. Nutritional problems would be more uniform on the plant.

Not sure what's happened to the sago,BUT, It sure is nice to have unautre and cycadjungle posting again!You both were missed and please stick around and share some of that knowledge. I,for one,appreciate you both.

When yall see nutritional problem ,What do i use?

If want try nutrition, you can find (expensive) packets of palm fert in Lowes, Home Depot.

If you are an Internet customer, Google for "Carl Pool Palm Food". It's made in TX but VitalEarth told me of only one retailer in SA

http://www.vitalearth.com/frame-right.htm

I agree that it could be mechanical damage.

I would put in the search cycad fertilizer. There is a difference between palms and fertilizer. Thats what I would do myself Im not saying the other info is bad. I had a problem with a king sago (common name)and I found out from cycadjungle what to do and it worked. Im not advertising for him but his site is awesome if you are a cycad lover.There you can find lots on how to grow cycads.

Definitely mechanical damage. I have a black walnut tree from which squirrels were constantly raining down nuts and nut fragments onto my sago. It got a lot of damaged leaflets just from that! Once the individual leaflets turn brown, they are dead. If it bothers you, you could go in and clip off the brown parts with a scissors, but that's rather tedious.