First, did you remember that you need to hold the thread tails when you start to sew? Either that, or start off your seam after putting the needle into the fabric. Either one will stop the thread nest on the bottom.
Did you grease the gears that the manual says to grease? I use tri-flow grease, but vaseline is a decent alternative. I got tri-flow at the local bike shop, but it's available on Amazon.
An old "trick" that I was recently reminded of is to put drop of 30 wt. motor oil on the upright gear that is just inside the hand wheel. The friend sent me a photo and I'll see if I can retrieve it. If so, I will post it later today. I've had a 301 for a few months, but just started to work on it/sew with it. It was either "whining" or "roaring" in that area. I oiled the area near that I guessed was causing the oil and it stopped. Meanwhile, a friend emailed me about the 30 wt. oil. I thought she might be wrong, as the noise stopped. I have not sewed anything in a week or so, but the noise came back. I used the 30 wt. drop of oil a couple of days ago. I have not had time to sew, so I don't know if it solved the problem or not. It certainly won't hurt. I had greased that gear with tri-flow, and it didn't stop the noise permanently. I will see the results later today.
bkay