repair Golden Tube SE40

Found Golden Tube SE 40 in basement. Left channel works fine except no sound from right channel. What is the best way to fix it? Could it be a tube problem or something more complicated
i'd see what's inside first if there's any traces of burning or capacitor leaks before swapping tubes from healthy to non-working channel.
Probably burnt resistors as several in the circuit are underrated. Contact Jeff Glowacki They are GT SE-40 specialists.