changing permalinks so I can use breadcrumbs plugin

I just realized to my horror that I chose stupid permalinks (I’ve already been pageranked for them and everything). What I should have done is category/page, but instead I used the stupid date format.

I tried switching it over briefly to use the jixor breadcrumbs plugin (I’m using 1.5). But I found my categories were showing up inconsistently. From what I could tell:

– top level categories showed up in expected ways.
https://www.domain.com/learn-about/ <- fine

– sublevel categories showed up with an unexpected prefix:
https://www.domain.com/category/learn-about/something/ <-bad

– strangely enough, main level categories seem to appear okay whether or not you use https://www.domain.com/learn-about or https://www.domain.com/category/learn-about (but subcategories don’t)

Needless to say this screwed up the breadcrumb attempt.

Any ideas about how to work around this or what’s happening?