There can be no examination of judges other than Impeachment proceeding and that has happened once early in our history-Justice Chase. He was not convicted. Separation of Powers as per the Constitution.
“There can be no examination of judges other than Impeachment proceeding”
Impeachment proceedings imply that impeachable offenses have been uncovered.
“Separation of powers”
Balance of power. The other two branches are supposed to keep an eye on the Judicial Branch. None of the three branches is empowered to police itself exclusively.
There seem to have been 15 federal judges impeached and 8 convicted
https://constitutionallawreporter.com/article-03-section-01/impeachment-of-federal-judges/