tech advise needed


I have an older threshold fet one pre amp
the other day it let out a "zittt "sound and shut off
the fuse didnt blow the on light is out and I have no sound

I opened it up and found a npn transistor shorted
my question is this something thats common? nothing else seems to be bad / just this transistor .I took them both out (there are 2 in the power supply and ordered new ones .should i dare just replace them and turn this thing back on ?

or get a new preamp ?
bigboystoys