Compromise of US KG-13 cipher machine?

The KG-13 was a cipher device used by the United States during the Cold War period. The Crypto museum page says:

‘KG-13 was a universal digital fully-transistorised full-duplex key generator, developed in the USA around 1963. It was intended for the encryption and decryption of external generated data, such as digitised voice and facsimile data.’

In the same page there is information pointing to its possible exploitation by the Soviet Union:

‘Between October 1982 and January 1983, whilst working at the US Air Force, electronics engineer James Atkinson discovered a series of serious flaws in the KOKEN stages of the KG-13's internal pseudo random stream generator [4]. Atkinson had been memorizing all current and historical circuit diagrams of the KG-13, the KY-3 and all of their FLYBALL modules, as a mental exercise. When going over the circuit diagram in his mind, he began to doubt its mathematical strength.

More than 20 years after the introduction of the KG-13, he was able to prove that most of the KOKEN stages were mathematically flawed, rendering the system compromised, and possibly leaking highly classified information to the Russians.’

The linkedin page of mr James Atkinson says:

KG-13 Encryption Sabotage Detection

October 1982 – January 1983

Complete memorization of all current and historical schematics and timing and logic charts of KG-13 and KY-3 encryption system.

Examining the schematics of the ciphers, key cards, as a mental memorization exercise, and then identified suspected flaws with the mathematic engines inside the equipment actually deployed.

Actually determined that most of the modules or "Koken stages" in the KG-13 were mathematically "flawed", and rendered compromised.

The cryptographic flaw enabled an eavesdropper to exploit all Top Secret data flowing thorough the "crown jewel systems" of U.S. Encryption called the KG-13.

An immediately and emergency modification to the circuits of the Koken stages resolved this matter, but not after it have been in place for over 20 years, and we had been leaking classified intelligence to the Russians.

The NSA was highly embarrassed at somebody finding this screw up merely by studying the schematics and logic tables, and finding what the NSA did not see for decades.

The end result was tens of million of dollars being spend to seal the breach.

I ended up being a rock-star of sorts within the technical counterintelligence circles.