That's a great idea with the counter weights. The motor I had only has the shaft sticking out on one end so I am only using one weight. I made a weight out of aluminum first but it wasn't heavy enough. Next I glued a strip of lead sheet to the aluminum weight but it still wasn't enough so I ended up making one out of brass. It seems to be a good setup now as too much vibration will start to effect the material moving up the belt. I also added a roller underneath along with a foam wiper and rails up the sides of the belt. I had to make adjustments during filming but after a few trips back into the shop it was working fairly well. I need to make some changes near the top of the belt as that is were dirt is being introduced onto the inside of it causing it to build up near the bottom roller. The wiper I made helps but isn't doing a great job. Next time I'm at a store I will be looking for a stiff brush. Perhaps a windshield scraper type brush will do the trick....
https://www.youtube.com/watch?v=iXGt...tJ-DusnO8Onw7A
https://www.youtube.com/watch?v=iB5s...tJ-DusnO8Onw7A