Washing machine was making noise when agitating & spinning

Then it started stopping in the middle of agitating or spinning, would smell like burnt rubber & the noise got worse, sounded like there were a bunch of marbles or rocks somewhere in the wash. It would restart again about an hour later, & repeat again-stop, smell burnt rubber, etc. My husband replaced the belt, wasn't it. This Saturday, we replaced the motor & it worked ok for about 15 minutes, it stopped again & smelled real bad burnt rubber, worse than before. Started up again but would only agitate, not spin or drain water, just a hum, then would stop. We drained the water by dropping the hose. When my husband checked the bottom of machine, the belt had turned the pulley black & looks like belt melted on pulley. Now it won't work at all, just hums.