susan, thank you for reporting this.
according to redhat, you're not supposed to modify anything in /usr/lib/systemd/system: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/sect-Managing_Services_with_systemd-Unit_Files.html perhaps weewx.service should go in /etc/systemd/system rather than /etc/systemd? or perhaps you need to do some black magic systemctl voodoo: systemctl daemon-reload and maybe slaughter a chicken just for good measure. m
