chicnhok,
Welcome to the Quilting Board forum.
Open your cabinet, raise that machine and get some Tri-Flow oil. Then oil it well. Oil the bearing parts of the treadle too.
That will reduce the friction greatly.
I've got two of the Singer 9W-7s and when cleaned and oiled they are very easy to turn. No effort at all.
Tri-Flow is available at Sew-Classic parts and most or many bicycle shops.
Clean the body with sewing machine oil and soft clothes or cottons balls to avoid damaging what's left of the machines finish and decals.
Joe