How about if in a state of confusion, pull one end of each diode (don't remove them, just lift one end of each.. )and verify that they are not leaky or shorted. A simple test would be to bias each of them with a 10k resistor a 0 to 10V variable power supply and a good dvm, you can even get better results if you measure the current flow through them as you raise the voltage. You should see them start conducting around .6 - .7 volts forward. Don't pay any attention to the board layout or schematic unless you physically draw it yourself from the actual printed circuit board, trace by trace.