Just acquired a model 6700 from Mom never used, is

Hi! Almost certainly! If I can find parts (and I can) for my turn-of the-last century-treadle machines, you'll be able to find parts for your Necchi. Here are a couple of good web sites for sewing machine parts. If you don't see what you need, you can email them and ask.
http://www.statewidesewing.com/#FAQ
http://sewingstyle.com/

That's for more specialized parts--needles, bobbins, and pressure feet are readily available for amost any machine. You just need to know what class of bobbin your machine uses (check your manual) and if you machine has a low shank, high shank, slant shank, or uses snap-on pressure feet. Your manual should say, but if it does, look at the machine. If there's about 1/2" clearance between the pressure foot and the throat plate, it's a low shank. High than that, it's a high shank. Slant shank machines have a definite forward slant to the shank of the pressure foot; they're pretty distinctive. Snap-on pressure feet have a little bar--you lower the pressure bar onto them and they snap in place. The snap-on unit can be removed (at least it can in the machines I own)--look for a thumbscrew on the side of the pressure bar--and with that off, they can use most low-shank feet.
I'm a fan of older machines!
Hope this helps!
Robbie