grmYour Cambridge AZUR 840C has a Sanyo SF-P101N laser/mech in it.
They cost under $10usd for the whole mech with laser, if you have just a little mechanical knowledge they take around 1/2hr to 1hr to install with no adjustments needed, $300usd is a ripoff, do it your self.
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR1.TRC0.A0.H0.TRS0&_nkw=Sanyo+SF-P101N&_sacat=0
Cheers George