How do I replace the motor pre-filter catch on my Dyson DC07?

The motor pre-filter catch (latch) on my Dyson DC07 vacuum cleaner broke off. I acquired a new catch (Part # 903346-01), but I have been unable to remove the old broken-off catch to permit installing the new one. I can see that the catch "clicks" into it's retainer by means of a raised tab, but gaining access to the underside of the retainer to disengage the tab to allow removal of the broken catch has me stymied.