Motor brake of Table saw

I own a Metabo tablesaw which I am very happy with. Some days ago, the motor brake stoped working. The blade turned for about 15 seconds instead of 3. You could hear a lot of bad, bad words in my shop. But it turned out, that it was my fault, not Metabos. By cutting some beech, the nut got a little bit loose. I never had conrolled that before. Excuse me, Metabo, for all these words!

-- Uwe from Germany.