Thanx SpritzerYou could replace the diodes (just match the current and voltage requirements) but I only do it if there is something suspect. They are run far under their rated values so there shouldn't be any issues. If you replace the diodes then I'd replace the bypass caps next to them as well.
Normal offset and balance adjustment as for all other Stax amps (well most) but remember that the pot marked offset is actually the balance and vice versa.
Do you see any advantage in replacing the 100uf power supply caps with something larger, say 200uf or even 500uf caps? The power supply seems to be unregulated ....