I dread having to dig inside my 520 if things ever go haywire but with the guidance of the group and some elmerly encouragement ya never know I might just get 'er done

I don't think you'll have much trouble working on the 520 -- of all
the rigs, it is probably the most serviceable. If you run into any
problems there are probably a few hams locally who will help you
out.

If the rig is in nice condition, consider finding a DG-5 which
serves as a digital display as well as a nice frequency counter.
And keep an eye open for a set of 6146s and a 12BY7 for spares.
There are some nice 520s on e-bay as well as the DG5. I had so
much fun with mine in the past that I almost feel like buying
another one for my self. I also had the SM-220 Monitor scope
which I still have and use with the TS-930. You can also get
a DS-1 (I think it was called) for 12V mobile operation!!! There
are more accessories -- remote VFO, VHF Transverter, and of
course the CW filters. You can have a lot of fun with a
TS520!

Go for it, and have fun! The more I think about it, the more
I feel like finding another one to fix up. It's just like
having a classic car!

Irv VE6BP