nakamichi pa5 or 7

what does that mean if the capacitator dry out, does the amp stop functioning. how do i know if my amp's capacitaor has dry out.

I am no expert either, but I heard that the sound changes for the worse - if you like what you are hearing, I would say don't worry about it. Depending on how the amp was used, it might be still ok - the temperature it was subjected to, and how much it was used.

I have even older stuff I still use without changing caps - 30 years old marantz 2270 receiver, and 20 years old Quad 405-2 amp.

I owned a Nakamichi PA5A MkII. This stock version had 150wpc with large heat sinks and never got hot. The earlier version had 100wpc w/no heat sinks and did get hot. Perhaps, Nakamichi changed the bias between the two versions. I was very happy with the MkII driving my speakers w/ribbon drivers. But, when I switched to electrostatics, the amp was unable power them. So, if you purchase this model Nak, be sure that your speakers aren't too demanding. I don't have any experience with the PA 7. You can find out more at AudioReview.com.

I think I burned the fuse on my PA5; anybody know the specs for a replacement fuse.

If the amp works when you get it perfectly, it will continue to work. Buy a pristine example and it will last you a lifetime as long as it has room to breathe. There are a few people online if you search forums online that will be of assistance if your amp has trouble, but based on the amps design, nothing will go wrong provided you have a 20A outlet and sufficient ventilation and you arent driving anything like electrostats. It will even drive maggies, however I wouldnt try to power any large monsters with the amp.