We use a white lithium grease (5 gal bucket) take out a gallonish and mix it with 1/4 quart diesel oil. Put it in a paint roller pan with a cover and have it in a tough box below the board. Works great and you can clearly see the shot. All in about $150 for a years worth. Most time you can just re roll it without adding anything to it and it will clear the pattern. We also added a drip tray for the environmental concerns.