I just checked all three of my sewing machines including the new Babylock Symphony that I bought this year. None of them are grounded. For older machines, just do a really good job of checking the cord. My old Singer has to have a new cord before I use it.

Also just an FYI some houses have the three prongs outlets that are suppose to be grounded but there is the possibility that the outlets are not grounded. We found this out on one house when we went to have some electrical work done on a house.