[morzh]

So far both 8uF caps' minuses are connected to the rect minus which is the centertap of the transformer's secondary winding, pin #4, and the 16uF's minus is grounded (chassis).


As for your hum....some hum may be normal - may be your grounding, may be something else.
But a question arises: you did not say if the radio was fully re-capped or you do not know that? Changing electrlytics solves the main problem but those tubular and backelite caps can still be leaky so it pays to replace them as well.