Hi Chris,
You have certainly a webserver configuration problem and I have no
experience on it. But, for permissions, you could check for all files
to be set to "read & execute". Only these files are updated
by operations:
wt_data_inc.php
wt_month_inc.php
realtime.txt
realtimegauge.txt (if SS Gauges)
content of folder include
Hope this will help a bit!
Regards,
Jacques