Zenith 7H918 FM Radio Restoration.

[Electronic M]

The original re rectifier was SELENIUM, and your 1n4004 is silicon. Silicon rectifiers date back to the 60s and unless subjected to over voltage, over current, or something else that exceeds specs will last pretty much indefinitely.
selenium dates back to the 30s was phased out in the 60s typically looks like a square plate tuning capacitor and let's out a stinky toxic smoke when it eventually burns out.