vncserver@:1.service still around after final SIGKILL. Entering failed mode.

I'm running centos 7 with tigervnc-server-1.8.0-13.el7.x86_64 and can't get vncserver to work.
Quote:

# systemctl status vncserver@:1.service a- vncserver@:1.service - Remote desktop service (VNC) Loaded: loaded (/etc/systemd/system/vncserver@:1.service; enabled; vendor preset: disabled) Active: failed (Result: timeout) since Sun 2020-03-22 13:00:11 GMT; 11min ago Process: 11164 ExecStop=/bin/sh -c /usr/bin/vncserver -kill %i > /dev/null 2>&1 || : (code=exited, status=0/SUCCESS) Process: 1572 ExecStart=/usr/sbin/runuser -l cent7 -c /usr/bin/vncserver %i -geometry 1440x900 (code=exited, status=0/SUCCESS) Process: 1552 ExecStartPre=/bin/sh -c /usr/bin/vncserver -kill %i > /dev/null 2>&1 || : (code=exited, status=0/SUCCESS) Main PID: 1869 Mar 20 09:03:07 cent7.svr systemd[1]: Starting Remote desktop service (VNC)... Mar 20 09:03:11 cent7.svr systemd[1]: Started Remote desktop service (VNC). Mar 22 12:54:10 cent7.svr systemd[1]: Stopping Remote desktop service (VNC)... Mar 22 12:55:41 cent7.svr systemd[1]: vncserver@:1.service stop-sigterm timed out. Killing. Mar 22 12:57:11 cent7.svr systemd[1]: vncserver@:1.service still around after SIGKILL. Ignoring. Mar 22 12:58:41 cent7.svr systemd[1]: vncserver@:1.service stop-final-sigterm timed out. Killing. Mar 22 13:00:11 cent7.svr systemd[1]: vncserver@:1.service still around after final SIGKILL. Entering failed mode. Mar 22 13:00:11 cent7.svr systemd[1]: Stopped Remote desktop service (VNC). Mar 22 13:00:11 cent7.svr systemd[1]: Unit vncserver@:1.service entered failed state. Mar 22 13:00:11 cent7.svr systemd[1]: vncserver@:1.service failed.

# systemctl start vncserver@:1.service
cursor just drops to the next line and hangs.
there's nothing in /tmp/.X11-unix/
# ps aux | grep vncserver gives nothing running
puzzled about this, thanks for any advice