+1 .... why do you REALLY want / NEED stretch....
there is a perfectly working iso with buster and linuxcnc 2.8.2 that is very easy quick and STABLE to install especially if you are having problems and are a relatively new user or one that does not want to fiddle under the bonnet.
quickest way to getting to cut chips >>>
www.linuxcnc.org/iso/linuxcnc-2.8.2-buster.iso
+ copy to usb using either:
www.balena.io/etcher/
rufus.ie/en/
reboot + access bios (delete / F2 / F10)
change boot order to USB first
reboot and install.....
done! Working config
fiddle with bios to improve latency
