Some days ago i recived a NES game. I didnt try it before today. When i started it, it was like 20% of the gfx missing. I tried to clean it alot, but still it had the same problem.

I then discovered that 1 of the pins (contacts) had its wire cut off, so there was no contact. I tried to solder it and it worked fine. But the problem is, soldering iron doesnt stick very good to plastic. It sticks, but a small movement or simular makes the iron fall of. Is there any other ways to make it to work?