I just got finished working on of these over, so I'll try to help answer some of your questions.
I found the KR6050 to be rather easy to work on: Everything is pretty accessible without requiring a lot of parts removal. Mine had a couple of bulging capacitors. I'm not quite sure which ones they were, (I've worked on something since then) but I'm pretty sure they were in the power supply. Those are probably the ones subjected to the harshest conditions. The caps on the output boards would probably be next. I recapped the whole thing: All the electrolytics, but you could probably leave the tuner alone. In fact, most people would probably advise you to leave the tuner alone if it works okay and you're not planning on getting it aligned. There's a thread somewhere on here about what you should do and should-not-do to a tuner, but suffice to say that you can make a mess if you fiddle with something without knowing what you're doing.
I neglected to look at your location, but if you're in the US, Mouser or Digikey would be the sources to look at for capacitors and most other components you might need. I've ordered from both and they're both excellent. If you can put together a list, you might try both places to see if one or the other is preferable for the items you need. One may not have everything the other has.
As far as what type of caps to use: If you've got a copy of the service manual (there's one in the database, I think, and if not let me know and I'll send you a pdf) you'll see that most of the electrolytic caps are just "general purpose" caps. There are a few low leakage types (LL) in there, and for those I'd use Nichicon KL series. For the gen purpose, almost any good quality cap would be fine, given the correct value and voltage. I prefer to use long life, high temp types if possible. Nichicon PW or HE are good... Panasonic FC, FM, FR. Several types from United Chemicon.. Everybody has an opinion about what's best. I generally don't go for the "audio" grade caps unless maybe it's in the signal path or something that might make a difference in a feedback loop, phono preamp... something like that. I'm not convinced there's that much difference in sound between various electrolytic caps. I DO usually try to replace small value electrolytics (like maybe 1uF or less) with film caps, if they'll fit, because I do think they sound better. Electrolytics are generally smaller than they used to be, and sometimes that means that you should pay attention to the lead spacing. Often times I'll go to a slightly higher voltage cap (like use a 25V in place of a 16V, don't go overboard) to get a size and lead spacing more like the original. There's not a lot of leaded 10000uf/50V caps to choose from for the main filter caps. I actually used some Nichicon FW, because that's what I had. The lead spacing was smaller than original, so it took a little modification to make them fit. Mostly what you'll find are snap-ins for those bigger caps, and you can generally make them work where a leaded cap had been, but it's easier if you can find one with leads.
As far as what else to replace: I wouldn't close it back up without replacing the speaker protection relay. I'm pretty sure this is the one you need, but I'm not at home now to check. So be sure and double-check for yourself before you order it.
http://www.mouser.com/Search/Produc...C24virtualkey65300000virtualkey653-MY4-02DC24
Another thing I would do is remove the output transistors from the heatsink (be careful with the mica insulators under them) and replace the thermal compound. You'll be removing the outputs from the heat sink anyway, if you replace the caps on the amp boards. One other thing: This receiver has pots to adjust the DC offset, but none to adjust the idle current, or bias. Instead, you get to change resistors and it's something of a trial-and-error process. Not an easy one either, since the resistors are on the amplifier boards, which are hard to get to without removing the output transistors from the heat sink. Fortunately there's a pretty wide range of acceptable bias current. Mine was right at the bottom, so I made an adjustment that basically doubled it. I can tell you the resistor values I changed if you need to know.
Most of the semiconductors are either going to be good or bad. And sometimes you may not find a problem until after you recap (see my recent KR6050 thread in this forum). The only other thing I generally do is replace zener diodes, and the only reason I do that is because they can get noisy- I wouldn't have guessed that, but I did experience it once- most values are available and they're generally pretty cheap.
Jason
