Hi. Our house is only ten years old and the gas furnace is large enough to heat the house but we are not getting heat up stairs. Do booster blowers work? I have heard before that duct cleaning is not a real reason... could it be?

Yes there are boosters but I would have your system checked over by a pro to make sure nothing is out of order to start with. It could be as easy as adjusting the dampers if the duct is so equipted.