If you like the sound of your current speakers (and it sounds like you do!

), I'd stick with them, just get the one that crackles repaired. Finding a pair of speakers you enjoy is the hardest part of this hobby, since they vary in sound more than any other component.
You might not even need to replace the tweeter. It sounds like it could just be a leaky cap on the crossover that needs replacing. That wouldn't be an expensive repair. If you replaced the (presumably) electrolytic cap with a better quality cap, you'd even improve the sound of the speakers in the process.
About your receiver: it looks like a good unit. Many of those vintage solid state units do sound good, even though 15 watts/channel is very low for a solid state amp. The one thing you should check, however, is whether it has developed DC offset over time. You can check this with a meter. It's possible that DC offset over time was what damaged your speaker. I'd check it just to be careful.
Your turntable is a good unit. I think it's the last thing I'd upgrade.
If you like the speakers, upgrading your amp is probably the most logical next move for you. There are so many great possible directions (a vintage NAD integrated with more power? a new JVC or Panasonic digital receiver? something with tubes?) that it's really up to you.
If you don't like the speakers, of course, I'd suggest you upgrade those first.