Bennett, some 301's have their feed dog knob stuck. I had one machine that I had to work on for quite some time. You just need to Triflow it and keep at it and it will turn, eventually. You will have better control if you can get that knob turning and lower the feed dogs.
Yes, the thread cutter needs to be removed depending on which FMQ foot you use. A couple of my 301's are missing their thread cutter as I suspect someone removed it for FMQ and then never put it back. The FMQing foot is loud, I agree!