diff --git a/Ploopy-Nano-Trackball-Kit-Assembly.md b/Ploopy-Nano-Trackball-Kit-Assembly.md
index aac94c2..1b86f3f 100644
--- a/Ploopy-Nano-Trackball-Kit-Assembly.md
+++ b/Ploopy-Nano-Trackball-Kit-Assembly.md
@@ -138,7 +138,8 @@ Prepare the following components:
 
 - This is an optional step. Only do this step if you complete the rest of the instructions and find that the cursor tracks poorly.
 - If the ball is very reflective, the reflectiveness of the ball will interfere with the function of the sensor, causing poor tracking.
-- A simple, effective fix is to get about a teaspoon of toothpaste onto the ball and rub it vigourously for about two minutes.
+- A simple, effective fix is to get about a teaspoon of toothpaste onto the ball and rub it for about ten seconds.
+- **HEY!** Did you read that? *Ten seconds!* If you need to, you can go longer the second time. But just go for ten seconds the first time! You don't want to make the ball a big scratched-up mess.
 - Toothpaste is quite abrasive, so it will effectively "sand" the ball, causing it to become less shiny. It will also cause the ball to smell great!
 - Once done, wash the ball (and your hands) well and try the ball again. The tracking should be greatly improved. If it isn't, try this step again.