VALUE OF NECCHI AUTOMATIC SUPERNOVA ULTRA MARK 2IN PERFECT CONDITION USED ONLY 2 OR 3 HOURS AND WELL TAKEN CARE OF

There is a button with two "prongs" or wings. Rotate the prongs clockwise about a quarter turn, to face the square mark (Q in the diagram) then press it down. It will stay down. To raise the feed dogs, turn the prongs anticlockwise (to S in eh diagram) and it will pop up
https://www.manualslib.com/manual/1205574/Necchi-Automatic-Supernova-Ultra-Mark-2.html?page=7#manual

In that case, I would assume a 'short' in the wiring. Which you could find with a current tester. Hubby has one, not that he has taught me how to use it. Or - My industrial machine has no light, so I've picked up a nifty folding lamp with ? - a light source that provides solar light spectrum. Check at thrift stores, or at any Wal-Mart. Not all that pricey, now.

check this link for parts and see if it's what you need

http://www.sewingpartsonline.com/necchi-supernova-ultra-mark-2-sewing-machine-parts.aspx

Just measure the existing belt and go from there. Besides the supernova and supernova ultra are likely to use the same belt.

Go to sewingpartsonline.com and you buy an instruction manual for $15. and they sell parts. Good luck

Did you wind a bobbin before this happened? If so, the winding features may be still engaged. Refer to the manual for this proceedure.

You may have to find a dealer who can help you with a replacement.

http://www.allynint.com/