If you have friends who sew, ask to try their machines to get acquainted with the newer features. Go to a sewing shop or two and have them demonstrate their machines with no intention of buying YET. You will be using this machine for a long time so make sure you are getting what you want. I would not be without a needle threader, a thread cutter, or the ability to make really nice buttonholes. I have a Pfaff with the built in walking foot and it is a valuable addition also. Shop for a while before you buy. It sounds like you might be having trouble with your machine motor when it gets "tired". Does the motor get hot?? If it's been serviced it shouldn't be an issue with oil, or worn parts.