I have always read that when you come across a piece of wood that is hard and difficult to carve, you can spray it with alcohol and it will become easier to carve. Some say the same goes for soaking the wood in water.
Like to sit on the swing and whittle and carve. A few weeks ago I was doing just that. I left a few pieces of Basswood sitting on the swing when I went in for dinner. After a week of travel I returned to the swing and found the wood. This wood carved like butter. The wood had not got wet in the rain, but the humidity was about 90% for the week, and the wood must have absorbed some moisture.