I agree with Metalsmith.
Search youtube for "Komatsu PC 45 Shortening Tracks" and you will see what is involved in breaking a track. I would be wary of why the 6-way blade is not working properly. Believe me, that's the only reason you would want this dozer. It would appear that this machine was repaired by a "farmer mechanic" -good enough to get it going. With a machine this old it has a "commercial use value" of $0. Unless you are a collector and want to pour money into it, I would look for a newer machine that still has some "commercial use value". These machines usually start their life in some construction job role. When they reach the end of their useful life in those roles they are usually sold to property owners who want to clear their land and when completed try to recoup their investment by selling it to another property owner. But there is a point where junk is ...junk.
Take some time and look for a machine that has some useful life to it. If you look at the online auction prices like Richie Bros. or Iron planet, etc. they set the going prices. You will pay the same price. If you want to buy local, ask excavating or construction companies if they are replacing any equipment.
That's what I did and I picked up a 2000 Komatsu PC50 excavator for $8,000. It was more money and less trouble then they would have gotten at an auction after paying commissions.
I am a rancher who has been in your exact position, looking at the exact type of machines. I got tired of working on and pouring money into junk.
I also recommend you get a midi or mini excavator instead of a dozer. My PC50 at 13,000lb with a grader blade will do anything my old 350 dozer did and more. Cheaper and easier to use and much more versatile.
Bjarn