Curious if the clamps on the glide bars of a Prince Neos 1000 machine ever wear out? I'm getting a loss of tension and have checked to make sure my tension head is calibrated. I've cleaned the clamps with rubbing alcohol thoroughly. I've also adjusted my clamps to the point where they are even barely crushing the string and I'm still getting some unusual loss in tension. Is there some texture or coating that comes on the clamp that gets smoothed out over time where the clamp needs to be replaced?