I don't know if it would be worth fixing, that would depend on how much money you are willing to spend and how much time you have to fix it, as well as if it was stored in a humid environment that solidified the toner etc etc. And of course the cost of a used 7760 in your area.
I can confirm the Accessories of the Phaser 7800 do not match those that go with the Phaser 7760
I have a 2010 Xerox 7700 with a booklet maker. Great machine until I had a toner and developer error/problem. I do printing from home and have a few other printers so I shelved the 7700 until I had time to sort it out.
It has now reached 2 years in storage and now I have time to figure things out. Is it work getting it fixed or should I replace it with another "new/used" 7700 so I dont have to buy the multi trays and booklet maker I already have?
Also will the new 7800 work with my current multi trays and booklet maker?