Page 89 of manual is the schematic. I would make sure your optos and switches are properly working and check both coils for proper wiring. If the gopher simply does not hold in the down position there are a few things that can cause it. If it is sensing in the opposite position i would look at sensors/ switches first.

http://mirror2.ipdb.org/files/4338/Williams_1997_No_Good_Gofers_Manual.pdf

It pops up and down when ball searching. Also if i recall correctly it can do this when the putt shot hole switch is flakey! I would look at the hole switch and trough switches in test. This is a stretch but just trying to brainstorm ideas. Best of luck