As for changing the belt itself, it seemed no matter what I did, if I got the 3-4 cams bang on and rotated the crank through 720°, it then threw the 1-2 cams out. Line 1-2 up and it then threw 3-4 out. I played cat & mouse with the damn things all afternoon going back & forth, but just couldn't get them happy. It was only a smidge advanced, but in the real world a smidge is actually a couple of degrees and I just couldn't get it to go back. The belt was straight, but I'd obviously missed something.
So I left it till the next morning, stripped the belt off and went back to square one. Nick and LC's clear instructions heeded, and it only took a couple of tweaks of the rollers to have everything lined up. Just to be sure, I then took the crank through a further 10 revolutions and this is how they lined up (which I was rather glad of, as I knew I'd have to report back here either way) ...
Whn I done the belt on my y26 first time I'd ever done a multicam belt, used to cavaliers and single belt mainly from my days in the trade, I followed the video (CD) on here and it seemed to work really well first time. 2nd time I done it, I was like this back and forth and couldn't get it right. I don't know how many times I started again, belt off again, but I eventually figured out the crank lock wasn't sitting right on the water pump, and every time I adjusted one bit, another bit went out. Glad I persevered as I got it bang on once fixed crank lock.
Could've easily said "That'll do it" and buttoned it up, but it's a really worthwhile learning curve to get it exactly right and follow instructions to a T.