I think you should get it repaired. It's likely something simple and you will get many more years of use out of it when it returns. The challenge will be finding someone to do the work for a reasonable fee.
And now back to the real world: Getting an older high current amp repaired can be a really bad use of funds when a newer (working) amp could be found for possibly less money, if money (or lack of it) is an issue. If the amp problem is "something simple" (what you've described sounds like anything but) you still could have a time bomb of leaky caps and whatever else can plague an older amp ready to fail. I'm not into wasting things, and maybe you could sell the Nak "as is" and put those likely small funds into one of thousands of newer amps, but a "reasonable fee" repair is often a fantasy.
It is a very good amp with a cultish following given that the design is attributed to Nelson Pass. So for an "audiophile" it is worth resuing. But as Wolf points out that is not the case here. The problem will be in matching the quality of the sound you had with the Stasis with an inexpensive new amp. There are some of course but you will have to specify a budget. A $500 amp is not expensive in these forums but might be twice what you want to pay.
BTW with $500 you might be able to repair and recap the amp you have now, but I wouldn't have anyway of knowing that for sure.