Joe Norton said:
Very basic question. Could someone remind me which leg is which on a
transistor, starting from the tag on the case.
If there is a tag it is indicating the emitter.
Tagged transistors are very uncommon today, so you will have to rely on
other methods. If we are talking about bipolar transistors they can be
described as two diodes and you can easily find these diodes with the
help of a diode tester (on a modern digital nultimeter).
When you have found the two diodes and how they are joined you know which
pin is the base.
To find out which of the other pins are emitter and collector you can
test both possibilities in the transistor tester. The combination which
gives the highest hFE is very likely to be the right combination.