Unless there was some significant value to the radio, or unless it has some historic value, there is nothing to be gained by fixing some old Japanese piece of junk.
By the time you fix it, you have as much in it as you would a good radio that works.
Individual components are very expensive today and the days of someone tinkering around with junk are pretty much over.

If it was a Collins, or a Heathkit or a Hallicrafters or a Hammurlund - there would probably be a dozen people wanting it, but not Yaesu..

The problem with companies like Yaesu and Kenwood and Icom is that once the radio is unsupported, you can't get the parts to fix it anymore.
The Memory chips and boards are almost non existent and you end up with a boat anchor.