Here is some commentary on the age/life of caps from an EE forum:
https://www.eeweb.com/forum/do-electrolytic-capacitors-age
No conclusive rules of thumbs, but I am guessing this receiver is 40 years old, so it sounds like the smart plan would be to plan on recapping it.
Does anyone have a good sense if there is a risk to trying it out? IOW, if the caps are bad would it result in damage to other components? Are there any other risk of plugging in a 40 year old "nib" receiver (as long as there are no signs of rats chewing the wires)?
@PENG, do you have any ideas on this?