Rockola 490-1 won't select

My 1984 Rockola 490-1 project establishes credit, accepts selection, but carriage spins continuously without stopping. It will, however, stop at home when no selection is made and service switch is put in "operate". This is my first electronic box; the service manual is useless as far as sequence of operations or troubleshooting guidance. Is there better literature for this mech somewhere, or can anyone provide me with some starting points? Im totally in the dark about the opto stuff. Thanks for any help! Carl.