Just to start, I don't know a whole lot about skidloaders, but willing to learn. I have a repair manual for this skidloader. After it warms up, it starts to knock, sometimes more then others. Have no idea where the knock comes from. this is a TM20, 3 cyl, about 2300 hours. Don't really know the history of the machine, bought it from a dealer who had it on coinsignment, from an older gentelmens hobby farm. Did not knock when I bought it. any help on how to troubleshoot or previous experiences appericated. Joe