GK MB2-500 Repair: Preliminary Q's

[Timefortea]

Good morning,

I am about to replace the icepower 125 power amp module in my Gallien Krueger MB2-500 because it has been stuck in safety mode for ~6 months now! It has been this long for me to source a cheap enough replacement 125. Now, I checked the jumper from the AUX power-in on the icepower and traced it back to the GK preamp where it connects to. The transistor there looks, well, interesting. A little smokey in colour and some of the writing has gone. Here are some pic's.

A shot from the back:


Here's a front shot - sorry if the quality is bad - but its not much better in real life!


Here's a comparison with a nearby transistor, notice it's not as dusty:


So, could this transistor be dead? Is it possible to test without removing it from the board?