Harman Kardon SR-300b FM tuner repair

[Arty30]

Hello all, I am doing my best to resurrect a mid-late 60s Harman Kardon receiver. It is a model 300b with just an FM tuner, the 400b was identical but with an AM tuner. I have gotten the amplifier section working apart from bad hum at any volume. I will tackle that later, but right now the tuner is completely dead apart from very faint music from somewhere. I have found a stronger source of sound around the tuning condenser and IF stages. It really doesn't help that there is no schematic anywhere so if anyone has a lead let me know. said source of sound doesn't really lead me anywhere else except to a little black 4 terminal device that looks like a transistor.  It says SES6518 and 157TID on it. I'll post a picture but I would like to try to identify it, whether is is a transistor or transistor pair of some sort. not having a schematic or good idea how tuners work it's hard to tell what part the signal is originating from and where it's going.

[fant]

Are transistor, 99,9 % germanium type.

Very difficult to find replacement.

My suggestion is to have a signal generator and follow the path of the RF.

Probably the IF is 10,7 MHz.
Without a signal generator and an oscilloscope, will be very difficult to find the trouble.

Mandi

[Arty30]

good to know, I have a scope and a 30MHz RF signal generator. I took some voltage measurements on the device in question and saw what seems to me like transistor like voltages. between the two outer pins was 0.7 to 1.5V, and other combinations was 6 to 8V. I couldn't really tell what could be the base, collector or emitter based on those numbers so I'm not sure what the pin is that has sound, whether it's the output or input to the device. there's just noise on all the other pins. I'm using a signal tracer by the way, a scope probe attached to an amplifier with a speaker.