The 227 might have the needle inserted wrong and/or be threaded wrong.
I had a 227M a couple of years ago. It did a fantastic buttonhole, and was the only machine I've had where the second round of stitches went directly over the first! Excellent machine.
Yes I think it had both problems , it sews beautifully as does the 15/91 . We got a much better deal buying both but I have to say I didn't know where I was going to put them but I found a way to fit them in
Boy, isn't that the truth! Truer words were never said. So glad you got them and found a place for them. It's not the getting them that is the challenge but the "where can I put them" that is.