Take the board out and use your multimeter to test the transistor and its predriver (the smaller three legged transistor associated with it). If either of them doesn't read the same as the same ones to either side, you'll need to replace it. It could also be the and gate or PIA, but that gets a bit more complicated to test.

Basically, put it in diode mode, and then put the dmm leads on two of the three legs of the transistor, and look at the reading. Then test the same two legs on another solenoid's transistor, and compare the readings. If they're more than .1V off, something's wrong. Usually they'll be really different though if something's wrong. Then, reverse the leads and check the same two legs of each transistor and compare. Do this process for all three combinations of legs (middle left, middle right, left right). If a transistor is bad, usually at least one of those six readings won't match another, good transistor's readings.