Kentia palm leaves lightening down middle

[HD3223]

Hi all, I have this large Kentia palm potted in my house (in Melbourne Australia).

I'm noticing the odd leaf getting a light strip down the middle? 

The palm is in the corner of the room and gets indirect light from 2 windows. We have central heating but I've closed off the vent nearest the palm. Its fertilised with osmocote controlled release at a weak amount. I have also got sulphate of potash magnesia but haven't used it on the palm.

 

Some of the lower fronds have a blotchy, yellowish appearance and are a bit curled but they've always been that way . Any tips? 

[HD3223]

I only purchased the palm a few weeks ago, I fertilized it lightly with osmocote and a tiny amount of sulphate of potash since, added some seaweed tonic. I've only watered it twice in 3 weeks using distilled water

[piping plovers]

I don't know what the light stripe is in the middle.  However,  I would be sure to check those yellow blotchy leaves in the bottom photos:  use a magnifying glass to see if there are red spider mites, any fine webbing.  Nice collection there of foliage plants.

[DCA_Palm_Fan]

It also  looks to me like it is lacking light.   Those fronds look very etiolated to me (stretched out) and a lack of light causes this.  

[PsyPalm]

@HD3223 each of the three howeas I've bought have gone through similar rehoming stress.  From the pics it doesn't look like you have anything too serious to worry about, in my experience when a howea goes from optimal growing conditions in a nursery to your home it's not uncommon for it to adjust by losing some of the smaller/older fronds.  It does however look like it might need a little more light than it currently gets in that right hand corner, you may consider swapping places with the plant in the left corner of the room by the couch, that way the taller fronds could enjoy the light from that high window as well as from the sliding door.  Beautiful specimen though:)