Pen shift funtion not working

[Sam.I]

In Illustrator I am trying to add a new point over the top of an existing anchor. I use to be able to press shift and it would convert to being a new point vs. adding to the existing line that I want to draw on top of. It does bring up a the X and Y location on the artboard, sometimes, but not consistently. I have already reset all my preferences to default, restarted illustrator, and restarted my computer. Any suggestions would be appreciated.

[Sam.I]

I know I can do this by locking the existing lines and drawing over, but I have a lot of drawing to do like this and it becomes very impractical.

[tromboniator]

Shift  + click works to start a new path over any interior anchor point of an existing path, but at an endpoint it continues the existing path. To start a new path, press and hold with the Pen tool, then press and hold the space bar and drag the Pen tool to the desired point, then release the space bar. Continue the path as usual. It helps to have enabled Smart Guides or Snap to Point to align the start of the new path to the existing point.

Peter