There could be other issues with your fork. Without pictures or inspecting it in person it is hard to tell for sure but it sounds like something else could be up. The bike is a low initial cost bike so be careful putting a lot into it especially if you need a new fork. Also keep in mind 1 1/8 threaded forks aren't common it was a cheap kludge for a lot of bike manufacturers making low cost bikes. It is becoming less and less common but is still practiced for some reason.
For those with 1" quill stems who want to go threadless and want a good clean look without having to change forks or deal with another quill stem try this:
https://www.innicycle.com/ I don't work for the company or get anything from it I just think it is a really nice product and super practical for those old bikes we love.