How to restart x11/StumpWM from a different tty.

Sometimes my graphic environment locks up. I think this is a StumpWM issue
since my keyboard and mouse continue to "work". I can move the mouse around
and switch to a different tty using ctrl-alt-f<n>. But nothing works in the
tty where I ran `startx`.

What can be done from a different tty to troubleshoot/fix the issue? I've
tried `stumpish` from another tty but I get the error `xprop: unable to
open display`.

Other possibly relevant info is that my `.xinitrc` launches StumpWM with
`dbus-launch --with-exit-session --sh-syntax stumpwm`.

Thanks,
Eric