If you look at the underside of the transistor,reading clockwise,starting at the tag ,the pins are: Emitter,Base,Collector.
As the 2N3906 is a PNP transistor,with your DMM set to the diode test position,place the negative (black) test probe on the base,& the positive probe on the collector & emitter in turn.
You should see the display for a forward biased diode in both cases.
Now,place the positive probe on the base & the negative probe on the collector & emitter in turn.
In this case,the DMM should show "OL" in both cases.
Place the negative probe on the collector,& the positive on the emitter.
You should again see "OL".
OK,here's where it gets disgusting!
With the negative on the collector,& positive on the emitter as before,spit on your finger,& use the finger to bridge between the collector & base.
If the transistor works,you should now see a reading on the DMM.--Take your finger away,the reading goes away!
What you are doing is biasing the transistor into conduction.
This trick works with most transistors,though some power types don't turn on enough to give a clear indication.
If you have to replace the 2N3906,you may have to use one in a TO92 package.If so,be careful to check the pinout of the new transistor before you fit it.
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