Broken tenons are a problem that's fairly common when bringing a beaten up piece of furniture back to life. The best option I've found in my time has been to create a floating tenon, but first you have to clean up the end grain nubs hanging out from the damage. A block plane works great for this
I cut mortises a number of different ways, depending on my morning tarot reading and the position of the spots on the sun relative to the phase of the moon. This time I fired up the drill press and hogged out the waste.
Then I cleaned up the mortise with a little chisel work. Because of the size of the pieces I decided it would be a good idea to downsize the mortise on the rail and leave a little more meat around the floating tenon, I had already cut the leg mortise bigger when I made this decision. This meant I had to do a little more work making a floating tenon to fit both sides.
With the structural repairs done I had another big decision. Try and fix the existing finish that was on the losing end of a twelve round prize fight or just take things back to bare and start from as close to scratch as possible.
I went back to square one with some sanding, some planing, and some scraping. The oak under the finish, beautiful.
Then I reassembled the leg section. The difference sitting next to the surviving leg was pretty striking.
Of course I had to take apart the other leg section and clean the crap off it as well.
Then I scrubbed the crap off the repaired table top and off the apron section and reassembled the desk.
The desk looked very different from were it started.
Ratione et Passionis