I bought a Minolta X-570 in 1985-86 and in 1999 it started doing the same thing. Sadly, because it didn't happen very often, I took it on my honeymoon in Germany. Disaster. I sent 12 rolls of film to the lab and was horrified when I got back around 100 prints. Total. I bought an X-700 new in 2000 and as of its last use last year, it still functions correctly. Knock on wood.
I'm not sure what causes it, age or use. I don't know how many rolls I shot with the 570 but the 700 has seen maybe 50 total. Year 2000 was probably the last year these could be bought new so the camera, and ALL X-700's are at least 15 years old now. Any one you buy is as likely to develop the problem. So, getting another might be cheaper, but you'd be better off getting that one repaired. I'd rather take a chance on a repaired camera than one that works right now but likely hasn't ever even had its light seals replaced.