As I am sure many of you have discovered, once friends and neighbours learn that you know which end of a screwdriver to hold, along comes a steady stream of "could you just look at this" type jobs. Yesterday I had a hedge trimmer passed to me, as, "it only made a noise and didnt cut". It is a Black & Decker, with their usual arrangement of a spiral gear formed into the armature shaft, running on to a larger nylon gear wheel. The gear on the armature is worn down almost to the root of the teeth. The nylon gear appears unworn. I checked, and the shaft is VERY hard, and yet has worn far mroe than the nylon. I have seen this happen before. Logically the nylon, being softer, would wear faster, but the reverse is the case. Any explanations anyone? alan@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx www.alanstepney.info Model Engineering, Steam Engine, and Railway technical pages. MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.