I have 2 of these punches. One is a button style that is 'fussy' - sometimes it will punches and other times I guess it doesn't feel like working. I found another one that is the lever style and you can't even 'feel' it punching but when you take the paper out, the corner is nicely done. Both of these punches are by Marvy so maybe it is the different style of punch that makes one work so much better than the other. SU used to sell this corner punch, don't know why they stopped. Like it because it is non-gender, you can wind twine or yarn in the notches or leave it plain.
Sorry you are having so much trouble with yours. Like you said maybe you just got a lemon.