To re-cap or not to re-cap? That is the question

You can pretty much leave all the film capacitors intact, unless they are showing any sign that they may have a problem.  If you MUST change them, a good brand is Mundorf.  But you dont have to go too fancy.  Some of them are ridiculously priced and you really do not need them.

As for electrolytics, after about 5-10 years, it is best to replace them all.  And when you do replace, if you can, substitute film capacitors into their place or choose higher voltage & temperature rated ones, if you can.  This may not be possible for larger caps since they just cannot make film capacitors of very hi capacitance values, but change as many as you can.

Here is an excellent site:
https://www.partsconnexion.com/film-capacitors.html

You got great answers on the caps. Safety trumps sound quality and those electrolytic's are past their expiration date. Quality modern electrolytic's are significantly better that vintage ones so they need replaced.

Jdane; Caps tubes cables do break in. The time varies in my experience. I've found at 50 hours things are settling in. After 100 hours you should hear little or no changes.

Thanks, everyone. Lots of well-informed advice here. I know what I have to do.

Mid40sguy--   I was being a bit facetious, but I guess the serious point was  that this is not step-wise?  (Perhaps someone can help me here).   I assume there is no difference between (1)  'break in' and  (2) 'aging' or 'degradation' (let's just talk tubes since no one doubts the aging process there).   It's just a slow degradation from the moment you turn them on until they wear out completely, with an (arbitrary?) period in the middle where we like them the best?   Not arguing here.  Just trying to figure out what happens.  Or are some arguing that once things get 'broken in', then they hit some steady-state of (perhaps finite) perfection?  

This comes up with all kinds of things,  just in my experience--physical books,  Mason jars, cars, sails, hair brushes, engines.    Is the process that electronic equipment is subject to different in any significant way?  (I would assume for some components it might be:  they either work perfectly or not at all, but in that case, there really is no 'break-in' period.).  Again, not arguing.  Just asking what audiophiles and electronics experts believe is happening.

All right, one final word, at least from me. And please: I promise I'm not trolling. 

I just got off the phone with the electrical engineer who repairs audio equipment in my community. I've worked with him for decades; he used to be the head of the tech team at the university where I teach before he started his private business as "The Audio Doctor." And, not irrelevantly, he describes himself as "a recovering audiophile." 

He insists that he has almost never seen capacitors fail, and that worrying about them "blowing up" and destroying the entire amp is plain silly. Active components like transistors, switches, and so forth constitute 95% of his repair work, he tells me. Moreover, he says that some electrolytic capacitors have "weep holes" that can leak electrolyte, and he has seen this problem (generally, the customer discovers some damage to the shelf on which the component with the leaking cap sits). Even with a capacitor that is leaking electrolyte, measurements will be within about 5% of what they should be. Furthermore, he says, circuits are very tolerant; most other components have normal functioning tolerances of 10% or higher. Bottom line: re-capping, he insists, will not improve my sound at all, nor am I risking a catastrophe from an old capacitor blowing up.

Now, I'm not saying he's right. But...I do trust him, he has 35 years of experience in the business of repairing audio equipment, and one would think he'd be motivated to suggest that I should replace my old capacitors, since I came to him wanting to do that, and he could have made money from me merely by agreeing to my wishes.

One more thing. My right speaker is more than 30 feet from my amp; the cable must go up and over a stone arch in my living room. The left speaker, however, is only a couple of feet from the amp. I've run 14 AWG copper wire--nothing special, that is--to both speakers, using the amount of wire I needed to reach the speaker. He insists this is completely fine, and gave me a long explanation of why I don't need to worry, which I'll spare you all. But I'm pretty sure just about everyone on this site will think I'm making a mistake not to buy expensive cable, and to run identical lengths of cable to both speakers.

Chances are, this thread is sleeping now. But it will be interesting to see if these remarks provoke a passionate response.