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The two connections across the 0.56 ohm resistor are current limit and current sense. When the voltage across the resistor reaches 0.7 volts, the current limiting begins at the output voltage will begin to decrease if the current is exceeded.
You need to accurately measure the 0.56 ohm resistor. If it has increased even slightly, you will see the problem you are exhibiting. But measure the voltage across it first for if the resistance increases, the voltage across it will increase. Right now it is designed to limit at just over 1 amp.
If the voltage across the resistor exceeds 0.6 volts, there is one of two problems: the resistor has increased in value and needs to be replaced or there is a problem with the circuitry downstream eg a leaky capacitor.
If the voltage remains below the 0.6v and the output voltage drrops, then there is a problem with the 723 circuit. If you have replaced the 723 with a known good one, I cannot see that there is a problem there.
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