D6D Track Frame Alignment

I bought a D6D dozer six months ago. I thought I had inspected it fairly well before I bought it, but it seems like the longer I own it, the more things I find that I overlooked.

The other day I noticed the track frame alignment is off in the rear. The sprockets on both sides are sitting to the inside of the rails. Clearance between the sprocket and the rail was only like 1/8" on the inside and it appears that at times they are rubbing.

So, what is the likely cause of this? I read that...

D6D Track Frame Alignment

D6D Track Frame Alignment