Suspected variable speed controller issue but maybe voltage regulator problem? The model and serial number plate on an Exmark zero turn is located under the lever on the right hand side, as shown in the image. Other places that the model and serial number plate could be located on an Exmark zero turn can be on the right side under the fuel tank, behind the operator seat, or on the right side of the operator console. However the exmark navigator is an IMPROVEMENT on the walker 1000 times. Everything that made the walker a pian in the neck to maintain, exmakr has addressed. The navigator has a bigger fuel tankand bigger grass hopper. Its gas tank also swivels out of the way so you can reach the engine, pulleys belts and balde clutch. Your Exmark model number can be found on the serial number plate, located in one of several various places depending on your equipment type. This plate will typically be black or silver. To locate the model number on your Exmark, click on your preferred equipment type below. Exmark Model Number Lookup - Select Your Equipment Type. Exmark Parts Lookup by Model. Hours of Operation.