i've managed to fix it myself - it appeared that the maemo 5 extras repository was installed & enabled, which (presumably) was making the application manager for the apps look for more advanced versions of the library incompatible with the device; i guess the previous owner might have been fiddling.

so for the benefit of anybody else who gets the same problem, here's how i solved it:

open application manager
from the menu bar at the top, select tools -> application catalogue
scroll down the list to maemo extras

there may be several so-labelled - if you edit them in turn, there may be one of them where the distribution is labelled fremantle - tick the box to disable that catalogue.

& then let the application manager whirr & grind to itself.

that way you should be able to install things previously broken.