Recently I have become aware that the gallery is not working properly. All looks ok until you click on a thumbnail and the larger image is not displayed. I think it could be due to different PHP versions from the old server to the new. For example clicking on http://www.elthammrc.org.au/index.php?option=com_joomgallery&func=detail&id=369&Itemid=102 and give a nice image, but it's blank.
I am investigating the issue and I will post any progress here.
I restored the files from my working version of the site from my home Linux server to the online version and it has fixed it.
I can only guess that one of the PHP files was corrupted and was outputting the incorrect ItemID=value as can be seen from the URL above.
Time to make a backup now that it's working correctly.