Both are the same in meaning, but "자꾸+만" has a stronger sense of "자꾸" like "한 번 더" and "한 번만 더" It is used when referring to something that happens over and over again and sometimes it makes you feel irritated, so that it is often used in negative situations. \^o^/

I can't find Jakkuman. I think 자꾸 = Keeps.