It's most likely the caps that are bad. Old electrolytic capacitors don't hold up over time especially after 47 years. The resistors should be fine as they tend to hold up well and when they go bad, it's usually pretty obvious (ie burned up). Well, except the carbon comp resistor on the supertweeter, those tend to drift wildly in value over the decades as they absorb moisture, but that wouldn't impact the tweeter that's not working. So, yeah, caps are likely the culprit. I'm actually surprised that they aren't giving you more problems. The 80?F is a common failure point with the DQ-10.
