Okay, that worked, thanks for the pointers.
For any other Noobs [like me], here's the steps I took the get my screensaver hack back working again:
Hotfix (Presumably, this re-initialised the Jailbreak)
Downloaded, and followed instructions to install:
JailBreak-1.14.N-FW-5.6.x-hotfix.zip
from:
https://www.mobileread.com/forums/sho...postcount=1597
KUAL (Kindle Unified Application Launcher)
Downloaded, and followed instructions to install:
KUAL-v2.5.zip
from:
https://www.mobileread.com/forums/sho...d.php?t=203326
MRPI (MobileRead Package Installer)
Downloaded, and followed instructions to install:
kual-mrinstaller-1.6.N.zip
from:
https://www.mobileread.com/forums/sho...d.php?t=251143
Screensaver Hack
Downloaded, and followed instructions to install:
kindle-linkss-0.24.N.zip and
kindle-python-0.14.N-touch_pw1.zip
from:
https://www.mobileread.com/forums/sho...d.php?t=195474
Hope that helps someone!