
The update installed successfully on the next attempt, but I found a few interesting pointers whilst checking out manual installs/uninstalls of IMF Updates.
There's a useful document from MS called the IMF v2 Operations Guide, linked from 907747.
You can manually install an update or go back to a recent version simply by registering the appropriate DLL and restarting IIS (run iisreset). Fire up a command prompt (Start > Run > CMD) and take a look at the pic below. The commands are:
cd exchsrvr\bin\MSCFV2\6.5.7993.0
regsvr32 MSExchange.UceContentFilter.dll
Note that if you try and register the MSExchange.UceContentFilter.dll from a different directory you'll get a 'module not found' error, so make sure you change to the correct directory first.

The original error listed in Update Services, top picture, should automatically clear after 24 hours - but it didn't, nor after a reboot. Giving it another 24h post reboot ...