the plastic slider is the issue. To fix requires removing the door panel, a trick in itself. If I remember, after all the screws are out it slides forward and up, also need to get into the vapor seal (plastic), be prepared to replace or repair.
You can sometimes work through a slit made by an exacto knife or similar.
The original plastic piece will have a rivot that will need to be drilled out, the new piece put back. I never really liked or trust my repair so I use the window sparingly.
Your window switches just need cleaned. They come apart have about 8 little ball bearings and copper rocker arms. take your time and clean everything and they will work like new.
good luck