Oh, by the way, checking a diode is easy.

Use a multimeter set to the ohms setting. You should have little resistance with the leads connected in the correct polarity, and infinite resistance with them connected with opposite polarity to the diode. Depending on the circuit, you may have to lift one leg of the diode out of the circuit to get an accurate test since other components may allow current to pass through, obfuscating your results. If the diode passes current in both directions, it's shorted. If it doesn't pass current in either direction, it's blown open.

J.