Hello,
Yes, 6 weeks is too young to be weaned completely. My Quakers wean at about 8 weeks and start to go to their new families at 10-12 weeks.
I would suggest the following:
-if the baby looks listless, or isn't perching, please take the bird to an avian vet right away.
-If his energy is good, but is begging all the time and does not seem to be eating enough, buy some baby parrot formula. I like Kaytee Exact Macaw formula. The instructions on the packaging are quite good. Start by feeding 7-10 cc's twice a day, then go to one time a day when the bird starts to lose interest in the formula. Continue to give the bird plenty of adult food and clean water. You are really just supplementing the bird's diet with the formula as it learns to eat the adult food.
-buy a gram scale from Walmart or Bed Bath Beyond and start weighing the bird first thing in the morning every day before feeding. You should see a consistent weight before you discontinue the formula. At 6 weeks, my guys are at their heaviest weight, then they drop a little and stabilize as they finish weaning.
Good luck and I hope this helps! Hand feeding is actually fun and a great way to bond a little more with your bird!