How do I repair the reverse linkage on a 1998 Honda Accord transmission?

How do troubleshoot and repair the reverse linkage on a 1998 Honda Accord transmission? The vehicle sat for about 1 year and now every time it's put in reverse, a grinding or slipping of gears sound comes from the upper half of the transmission. Prior to sitting up, the car ran perfectly fine. It sounds alot like a starter when it doesn't completely engage the actuator gear. Does this transmission contain any sensors or pressure valves that could be the cause?