Thanks heaps for your responses guys.
This is the output from systemctl status smbd.service -l, so it appears it is running.
root@sulaco:/# systemctl status smbd.service -l
● smbd.service - LSB: start Samba SMB/CIFS daemon (smbd)
Loaded: loaded (/etc/init.d/smbd)
Active: active (exited) since Tue 2017-04-04 20:14:40 AEST; 15h ago
Apr 04 20:14:40 sulaco smbd[7516]: Starting SMB/CIFS daemon: smbd.
Apr 04 20:14:40 sulaco systemd[1]: Started LSB: start Samba SMB/CIFS daemon (smbd).