I am referring to the little white or plastic disks that the springs rebound off of. I have been having trouble with getting this old yamaha horn up and running and the last obstacle is trying to figure out why the 3rd valve is sticking pretty badly. Badly enough so that the horn is not playable with that valve stuck. I cleaned the crap out of the horn, piston, everything! New oil, the works. Then upon really close inspection I noticed that the plastic discs on valves 1 and 2 are identical, so I made sure the 3rd was aligned the same. Well, sure enough, it wasn't. Once I realigned the disk after taking the piston apart, the horn began to blow freely and normally. Great! Only problem is this though, the stupid valve still sticks. So upon even CLOSER inspection, it looks like there is a slight imperfection on one of the 2 'prongs' coming from the disc. Looks like maybe a tad bit of the plastic broke off one side of the prong. And I don't really know much about mechanical issues, but this seems to be looking me right in the eyes. You guys think this could be the cause? And if so, this part can't cost more than 2cents to make, but where in the world can I find it so I can test out the fix?!