Quick GIF Disposal Fix
A downloadable tool
Information Thread: http://pixelation.org/index.php?topic=20505.0
This simple script works with Gifsicle to try to unmerge frames in the input GIF file. It does so by changing the frame disposal of the frames.
1. Download a Windows build of Gifsicle from here: https://www.lcdf.org/gifsicle/ (Click Windows Ports.)
2. Extract it.
3. Copy "giffix.bat" to the same folder as "gifsicle.exe"
4. Drag your broken .gif file over "giffix.bat"
You'll get eight files ([originalfilename]_0.gif through [originalfilename]_7.gif) one of which may have the frames unmerged.
Disclaimer: This .bat will overwrite [originalfilename]_0.gif through [originalfilename]_7.gif without asking. If you have files named like that you want to keep, move them before dragging [originalfilename] over the .bat.
If your GIF actually did require different types of disposal in the same animation, this won't give you a single file you can continue from. It may still split the frames you're looking to split so you can copy them back to your original file.
I am not responsible Gifsicle itself, nor the Windows ports. This script is provided as is with no warranty or guarantee of support.