Jacqueline Fauria m wrote:

I need to replace the chuck on my dewalt dw106 type 1 drill but the chuck is
stuck in the full open position. That's why it needs replaced. How can I get
the pieces apart if I can't tighten an Allen wrench down in it

Grip the chuck with vise grips or a pipe wrench and whack it with a whammer.
https://www.youtube.com/watch?v=ItbfakGEBG4