glock backplate problem

I have recently started putting together the upper for a G43 build. I know your supposed to hear a click once the slide plate has locked in place but mine has not made that sound once it is pushed into place. There is also a visible gap between the slide plate and top of the slide. Has anyone...

I was finishing my slide and when I went to put the backplate in, it was crooked (picture provided). I fooled around with it and discovered that the problem lies within the extractor assembly. The backplate will go on without the firing pin assembly, but gets hung on something. There are no burs...