Nor 65, welcome aboard !!!
Start posting your problems with your newly acquired bike, we live for this .
Your stiff throttle, may be the throttle tube, that the rubber grip goes over, it's got gear teeth, where it mates up to the cam gear in the throttle housing .
Neither part is made of the most robust materials, and it's not uncommon for the teeth to get worn, and give you a stiff, or tight throttle feel .
You've got a lot of winter ahead of you, so the bike should be ready to go, come warm weather next spring .