If you are experiencing an issue with your Gradall, check the fuel level and make sure the fuel shutoff valve is in the 'On' position. Check the battery connections and make sure the battery is charged. Check the oil level and make sure it is at the correct level. Check the air filter and make sure it is clean. If the problem persists, it may be necessary to bring the Gradall to a mechanic or service center for further diagnosis and repair.