Here is a pic of the rear rack on my 610. As you can see it need to be bent/centered. Not sure how to proceed. Should I do it on the frame or pull it off and bend it and then re-install.

I wouldn't.

Just me, though.

I wouldn't bend an aluminum rack either.

I've bent old solid-rod aluminum racks (like yours) back while they're mounted on the bike. Just pull on it with increasing degrees of pressure, and don't use anything that extends your leverage i.e. tools. If you break it by hand, it was on it's way out anyway.

My .02, but I'm a welder so breaking a rack isn't an end-all be-all in my particular circumstance.

You could probably get it back to center with a little gentle persuasion. While on the bike.

I know from hard-won experience that aluminum alloy doesn't like to be bent more than once, but having it off-kilter would drive crazier than having to find a new rack.

Those racks are made of fairly soft aluminum so a little bit of correction shouldn't be an issue.

i made my moto grand record my grocery getter. i already had a cool, center-mount blackburn rack i polished up. it looks great with its new black/red banjo brothers grocery pannier to match the paint. [skip ahead six months] ... i notice the rack is now leaning to the panner side. to bend back or not? nah, i just started putting the pannier on the other side...

While aluminum isn't nearly as tough as steel, that's not much of a bend to straighten it. The elongation percentage of any given area in that rack is probably quite small, bending it back would weaken plastically deformed areas (fancy way of saying bending it permanently), but not by a whole lot.

Aluminum racks typically break at the welds, or at high stress areas like attachment points. If you do bend it back, do as others have noted, start with a little force and work your way up until the rack is centered on the bike. Check the attachment points and welds afterwards.