From the Manual:
Additional features of the ?POWER TUBE BIAS SECTION?
Fast Blo fuses. One per output tube. In the event of a power tube failure, the corresponding fuse will open protecting the amp from additional
damage. A red LED next to the fuse will indicate that the fuse is blown. If this happened in the past, you would need to take the
amp to a repair shop. They would then hold it for ransom while you figured out how to raise enough money to pay them to fix it. No
more. The amp will now tell you if you have a shorted output tube and which one it is! With the power off, simply remove the power
tubes and replace the indicated fuse with a FAST BLO 250mA (1/4 amp). NEVER EVER use anything but a FAST BLO 250mA (1/4
amp) fuse. If you do have the misfortune of ?blowing? an output tube, we strongly suggest replacing the pair. Remember, your amp will
only perform as well as your weakest tube.
