Hey ray,
I would replace all the small signal transistors.
usually one or more are defective.
marantz put the original footprint on the boards. But used backward footprint transistors. Note that the newer transistor fit perfectly except for the Differential amplifier 2x7B ---> 7A fitting. these are the only two transistors that go backwards see photo's on my thread.
I use: Bc546 556 and MPSA92 and MPSA42(high power section).
and i think one BC 550 somewhere.
Jon