Fun conclusion post. Short story:
Turned out to be the one that I actually thought was ok and the auto tensioner is frickin' near impossible to remove without removing the PS pump/pulley....read on
As above the auto tensioner and upper idler had play and probably needed replacing, but the lower idler which had no play had clear evidence that it was rubbing on the long mounting bolt. Seems the lower idler actually has two? bearings inside and from what I could see the inner bearing seal had gone a long time ago. The inner race was rubbing on the bolt, you could see the shiny patch where it made contact on removal.
Fun fact #1
the Gates part is almost twice the Dayco price for this pulley, I went Dayco for this part and saved $30 (~50%)
Fun fact #2
the Gates parts come with new bolts and dust shields, which are useless, I couldn't even get a stubby 17mm socket on the replacement bolt, even using a simple 3/8" breaker...just wouldn't fit. I cleaned up the original shields (much better quality) and re-used the original 13mm bolt. Next time I'll just buy all Dayco and not pay 'extra' for the useless hardware included with the Gates parts.
Fun fact #3
the top auto tensioner assembly mounting bolt is directly behind the outer rim of the PS pulley. No way you can get any kind of socket on this. I wound up using extra long box end 13mm wrench with a slight angle of 15'?? I was just able to get this on enough of the bolt head to break it loose, then had to put it on another 50x to get the bolt far enough out to remove with fingers
Fun fact #4
You cannot remove both the upper and lower auto tensioner bolts with tensioner in the same position. The lower only comes out when the tensioner is free, and the upper only comes out when the tensioner is locked in place with your 6mm allen key through both holes. So this means you have to lock it to remove the belt, unlock to loosen but not remove the lower bolt, relock it and work on the upper bolt, then careful unlock it again to remove the lower bolt and assembly. Installation is the reverse of this nightmare.
Fun fact #5
For whatever reason I removed mine still in the locked position...so to get your allen key back out...I used some vice grips to 'pinch' the two parts enough to remove the key, but when you unlock the vicegrips...it expands more than they do, so you have to tap the tensioner off the vicegrips...sigh.
All good now though...$180CDN later (I put a new belt on too).