Abstract: An x-y axis guiding apparatus is utilized as the guiding mechanism for a laser marking device. Wear compensating bearings are utilized in conjunction with the x-y axis guiding apparatus so that the gaps between the bearings and the guide components which occur as the bearings wear is taken up and the desired precision maintained.

Abstract: A portable testing device for seed tube and combine sensors is provided for checking the operability of the sensor in situ at the time a problem arises in the agricultural implement. The testing device includes a housing in which is mounted a printed circuit board and a battery for providing an electrical current to the components on the circuit board. The circuit board includes an on/off switch and an LED. An electrical coupler allows the device to be quickly and easily attached to the coupler of the planter harness so as to check the operability of a seed tube sensor. In operation, the LED blinks on and off when the sensor is properly operating, and remains lit when the sensor is malfunctioning.