If it is on a Nytro with the maverick track. 400 km's is alot of km's on sliders!
The fix!
1. change tracks (or remove/replace the cheese grater clips off of the maverick)
2. Polaris hyfax (way better than Yammie not sure if they directly fit on yamaha rails)
3. Scratchers will help alot!
I had that problem too. I mounted Slidekick scratchers as far forward as possible and I just moved some idler wheels to the inside ahead of the tip up which is where I wore the most. Seems to be working. Also make sure you get the Yamaha graphite hyfax on there, they last alot longer than the regular ones.