Chick not feathering out

It's 35 mins till midnight here so I'll get photos posted tomorrow. I have a chick who looks the same now as it did 2 weeks ago, its barely grown or feathered out, it still has baby fuzz however its very thin baby fuzz and there isn't much of it, in fact my 2 day old chicks have more and better thicker baby fuzz.

Anyways its a non frizzled faverolles cross and all its hatch mates/ brothers and sisters are growing accordingly and feathering out nicely. I currently have it in with my youngest chicks under a light and on a heat pad to keep it warm.

It is getting medicated chick crumble, the best brand we have and have used this brand for 10 years, the chicks also get meat scraps and b vitamins and vit e and selenium tablets each day ( crushed into their meat scraps) and this chick has a normal eating and drinking .

This is the second chick in 14 years I've had with this problem and that chick died at 9 weeks old it never grew past the size of a 3 week old and it had baby fuzz still, the only way to tell it was older were its wing feathers .

Any suggestions, ideas or stories would be very helpful and much appreciated