primera starter motor

I seem to remember seeing in this group problems with primera starter motors. Not thinking anything of it at the time, I now have this problem. I have a 1993 nissan primera SLX (69k miles). Ocassionally, when I try to start, something just spins and that's about it. After a few goes, however, it turns over. As I am expecting this problem to go worse, is it usually the motor that goes or is it the starting ring. Is the motor easy to fit? I'm ok - ish on maintenance. Any help would be appreciated. Thanks glenn