@RadioLab I don't it's advisable to use external DC-DC unless you're completely sure that you're replicating the original signal exactly. Download the SMD code book, find out what the transistor code stands for. If it's a simple NPN transistor in SOT-23 package you can find any NPN transistor from either Fairchild Semiconductors or Motorola from farnell. It's easy to replace. If you don't have much soldering experience you can go to your nearest RadioShack and find someone to do it or you. It's better to get a simple OST-23 transistor replaced then having to deal with a board with multiple components malfunctioning.