Cheers John, my own research and talking to Nissan tech's show the early K12 2002/2003 had a crap batch of chains which were made of chocolate!! The chain stretches to such an extent that the tensioner piston which is usual out @ 8-10mm is showing 20mm!! Your post confirms what I have read, ie; engine/box out, I was hoping someone had a rough price guide to do the job, Nissan are looking at £800 - £1000!! I've seen the chain kit, ie; chain, tensioner, guides, both cam cogs, one of which controls the VVT, going on ebay for up to £300!! This looks to be an expensive repair for what is essensially a nice cheap little car.