Rollers or slider?

[cosworth34677]

I am having a time with this dozer build. I can't seem to get the tracks to run smooth. I am using the vex tank track kit. It works but the bogie wheels S straddle the chain in the tacks. And this was clogging up the tracks and causing all kind of problems. So I made a set of rollers and they didn't work well. So I will took off the roller and ran it and it seem to work the best this way. So....... do I try to make a new set of rollers or get some slick plastic and make a slider? I just need to keep the tracks from bunching up when reversing help please