Don't do it. Show us a picture of your Necchi. I just saw one over Christmas that was stunning in design, still worked great, and was older than me (and I am 51). I wanted it but shipping it here would have been prohibitive even if I could have talked the owner out of it.
I have a 30 YO Bernina and a 40 YO Elna. Both are great machines, the Elna needed parts when I first got it and people DO fix sewing machines.
So get it tuned up, keep the Brother as your backup.
tim in san jose