Antecedent question

[flysoohigh63]

Can someone clear my doubts on the following sentence?

p.36 Foundations of GMAT Verbal:
'Flawed in two ways, the earthquake detection system would often find a geological precursor event when it wasn't actually occurring and fail to find it when it was.'

This sentence seems to be somewhat relevant in structure to the following one: (p.31 Foundations of GMAT Verbal)
'Representative Nancy Pelosi and the lobbyist had a heated disagreement about her agenda'

In the last sentence it's not clear to what antecedent pronoun 'her' refers to.
So in the first sentence 'it' theoretically can refer to 'event' or 'system', but logically only 'event' can 'occur', so we can conclude that 'it' refers to 'event'.

So my questions are:
Is my reasoning correct?
And is it ok to use sentences on GMAT, where pronoun reference to antecedent can only be determined by logic?

Thanks!

[RonPurewal]

Your reasoning is correct. More importantly, though, you really shouldn't worry about this, because "pronoun ambiguity" has not ever been tested on the current version of the gmat. (I.e., the current gmat has never contained a question like the Nancy Pelosi one.)