'83 window out of track

The power window on my '83 comes out of the track when putting it up. There is a black triangular clip on the back upper corner of the driver side window that pops out and then the window falls forward back down inside the door.
If I snap that clip back in the window will usually go up but sometimes pops right back out again. Sometimes it binds inside the door and is very difficult to raise.

How do I fix this and how do I remove the interior trim panel to get inside the door to effect repairs?

Thanks,
Dave

The power window on my '83 comes out of the track when putting it up. There is a black triangular clip on the back upper corner of the driver side window that pops out and then the window falls forward back down inside the door.
If I snap that clip back in the window will usually go up but sometimes pops right back out again. Sometimes it binds inside the door and is very difficult to raise.

How do I fix this and how do I remove the interior trim panel to get inside the door to effect repairs?

Thanks,
Dave

The black thing is called a window guide and you can pick these up from a GM Goodwrench service center for like a buck or two apiece. What's happened is yours probably broke or wore out so now it won't stay tracked. Replace this, then shove the window into the track and life should be good.