That's the bolt I couldn't move.
Even after a night of penetrating oil I nearly rocked the ST off the stands getting it loose.
Put some blue threadlock on before putting it back in.
Looks pretty good from a distance.
This is the belt I replaced.
I suspect it had been replaced by the PO.
This is the belt tensioner.
In this pic, it's completely loosened, with the lower tab off its locating pin.
In this pic, you can see the lower tab on its locating pin.
I found it easiest to get the tab back on the pin without the spring on, put the belt on, then replace the spring.
I'd read other write-ups about this service and none mentioned having to rotate the belt 2-4 times before tightening the bolt on the tensioner.
Read the manuall!
Upon closer inspection there was some grime in there.
And a bit more grime.