My brother tried cutting a spot he'd let get high with a Yardman/MTD. He was stalling and squalling belts. He quit and said have to get bush hog. I told him I'd cut it. He asked what with. I said my 30" Snapper, he laughed. I mowed it, he asked why it would do what his couldn't. I said in a feminine voice, yours is for clipping the lawn, switched to masculine, said mine's for cutting the grass. One long blade with high tip speed and one belt, two pulleys VS two, short, slow tip speed blades, buncha pulleys and long convoluted belt(s).
You're trying to bush hog too fast with a lawn clipper. That front blade isn't able to hold speed.