Thanks for the response, I've just tried again following your steps first but exactly the same happens....
Anything else I can try?
This is the log from the install:
Feb 22 12:12:43 Tower in.telnetd[5604]: connect from 192.168.1.1 (192.168.1.1)
Feb 22 12:12:50 Tower login[5605]: ROOT LOGIN on '/dev/pts/0' from 'Mike-PC.home'
Feb 22 12:18:08 Tower emhttp: cmd: /usr/local/emhttp/plugins/dynamix.plugin.manager/scripts/plugin install https://raw.githubusercontent.com/jbrodriguez/unraid/master/plugins/unbalance.plg
Feb 22 12:18:09 Tower root: plugin: creating: /boot/config/plugins/unbalance/unbalance-2.1.0.tgz - downloading from URL https://github.com/jbrodriguez/unbalance/releases/download/2.1.0/unbalance-2.1.0.tgz
Feb 22 12:18:11 Tower root: plugin: checking: /boot/config/plugins/unbalance/unbalance-2.1.0.tgz - MD5
Feb 22 12:18:11 Tower root: plugin: creating: /boot/config/plugins/unbalance/unbalance.cfg - from INLINE content
Feb 22 12:18:11 Tower root: plugin: running: anonymous
Feb 22 12:18:11 Tower root: plugin: creating: /tmp/unbalance-chkconf - from INLINE content
Feb 22 12:18:11 Tower root: plugin: running: /tmp/unbalance-chkconf
Feb 22 12:18:42 Tower php: /usr/local/emhttp/plugins/unbalance/scripts/start
Feb 22 12:18:42 Tower sudo: root : TTY=unknown ; PWD=/usr/local/emhttp ; USER=nobody ; COMMAND=/bin/bash -c /usr/local/emhttp/plugins/unbalance/unbalance -port 6237
thanks, Mike