Harmonic balancer 340

What are the chances your thrust bearing is kapput? I think there's only about 1/8 " to be had there, but I guess it's worth a check.
I pulled a teener once, with a shot bearing. The TC bolts were cutting a channel into the back of the block already.They had "machined" their way into the rear cam plug. It required brazing to repair, and the crank was junk. I think I tossed the rods too. The block lived. It became my winter motor, years ago.I can't say it's related but the tranny behind it was puking oil too.

Easy check; just pry the balancer forward, then push it to the rear. End play usually falls around .007 to .010. It should not "clunk". .010 is about the thickness of two or three pages of newspapers.
Yes you need a special tool to pull that balancer off. And a longer bolt plus some anti-seize to reinstall it.
I'm not sure removing it will accomplish anything. There's nothing in there to prevent the balancer from seating. With the possible exception of the oil flinger. I suppose it could have become dislocated from the key during a careless damper install, but that's nearly impossible. Even if it was on backwards, once the cover is on, I don't think it can move forward enough to come past the key.Anybody know for sure?