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Those are silicon transistors. The hiss may well be due to a noisy first amplifier transistor but don't rule out a bad resistor.
Biasing for both transistors determines the required beta of a replacement. Generally, any common NPN will do, such as 2N2222A or 2N3904 or whatever you have in the junk box.
If the hiss is present with volume set at zero, suspect also the 2.7 Megohm resistor in the base.
The electrolytic coupling capacitor may be leaky.
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