ISZKAV23 belt tension and electric clutch noise?

Just purchased a used FERRIS ISZKAV23, the 23HP Kawasaki runs great, but I am having some issues with the deck belt slipping and some strange noise from the PTO clutch area.

If the PTO clutch air gap isn't adjusted properly can it make a "dragging/grinding" noise?

Also, I am getting belt slip in medium height of grass... Where is belt tension adjusted on this mower and how tight should it be?

Thanks! New member here.

TFB