I inherited a site, and image galleries appear in the Joomla! article pages HTML  using {gallery}...{/gallery} tags all over.  These work fine.

Problem is on some article pages the gallery tags are not used but rather a block of code is found in the page HTML, viewed in Joomla!s tinymce editor, starting with:
<!-- JoomlaWorks "Simple Image Gallery PRO" Plugin (v2.0.4) starts here -->
And ending with a similar comment.  This code displays a thumbnail image that links to another Joomla! article instead of displaying an image gallery.  The problem is the thumbnail image disappears in both tinymce editor and on the site after the article edit is saved even when no editing changes are made. 

How to edit these articles without breaking the image links?  And how did those image links get into the article in the first place?  This site is seriously broken until I find the answer.  Any documentation from JoomlaWorks on using the thumbnails as article links?  Thanks.

Problem solved: 
TimyMCE whacks the Simple Image Gallery code on article save.  So I unset TinyMCE as the editor in Joomla Site:Global Config.  This makes the article edit window display raw code, nice ehh?

I then copied in an unwhacked SIG code block from another page, and fixed it up with appropriate ID elements from the whacked block, then deleted that one, and it worked.