When I installed my water heater 5 years ago, I modified the stair tread for easy removal in anticipation of future anode inspections/replacements–so replacement with another solid rod should be a straightforward process.
After installation of the water heater back then, there was evidence that it had a slight leak at the hot water port. I never messed with it but the leak seemed to eventually stop. Anyway, when I get the main anode replaced, I intend to extract the combo rod and parts for inspection and redo the threaded fittings there to attempt a more positive seal. Pipe dope was used that time but I plan to redo with tape.