Do you know the temps in his box? it is very important we keep track of that because they can get over heated under heat too. Or too cold you can usually tell if too cold they will be directly under the heat or too hot they will get as far away as possible. Hopefully he has a box big enough he can get out from under it if he gets to warm. An inexpensive thermometer will be good to have.Place heat lamp at one end if you have it right in the middle so he can get away from heat if he wants. When i had my tiny duckling in just hatched I had a towel I kept over my shoulder and when I'd sit down he would climb under that towel in the crook of my arm and sleep just like he was getting under mamas feathers. What is your house temp? First week the temps in brooder should be 85-90 I always kept them at 85 in a non draft room each week there after 5* lower. till they are feathered in so by by week 6 they are able to handle 60* temps.
When I say a towel over my shoulder most of the towel was hanging down in front just enough towel over my shoulder to hold it in place. They love to snuggle up around your neck too.
are you talking about FULL Feathering at 6 weeks? Because I have see adult feathers coming in at 3 weeks. My seven babies are outside right now and they are only 4 weeks but they have a lot of adult feathers in already.