[vacri]

It's the retailer's responsibility - after all, the manufacturer might not even have a channel for the general public to access, or even go by the branding on their parts.

The problem is as elithrar points out - 'doing something about it' doesn't necessarily mean 'replaced right now'. Responsibility for the repair may lie with the manufacturer, but the retailer sold the goods - if they're faulty, then it is the retailer's responsibility to make good on them. Just as it's the manufacturer's responsibility to make good on faults encountered by the retailer.

MSY (a super-cheap retailer) got slapped for foisting warranties back onto the manufacturer, and 'now honour warranties' (see section 2 here http://www.msy.com.au/pdf/TermsofTrade.pdf).