Definitely fixable. With a bit of research, sounds like something you could do yourself for under $50, or (I'm much less certain here) about $150 if you were to pay a competent and honorable mechanic. Note that I'm not considering tires - which could be significant if they need to be replaced and depending on what your criteria for that is.
The PX-10 is one of the most iconic models of the 1965 - 1975 era. Unless it is a bike that it can be proven that Eddy rode, you're not likely to reap a great financial reward from this if your objective would be to sell it, but speaking from the standpoint of pure sentiment, and enjoying taking a ride on it on nice days, this could be priceless.
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