Marantz Twenty-Two Loud Hum only warm one channel

[Blubau]

This is my first post to the forum so excuse me in advance.

I have a model Twenty-Two that I acquired with issues. It had some distortion in one channel that was repaired by replacing the large filter caps in the power supply.
It also has another issue that the cap replacement did not repair. Once the unit has been operated with any input for several minutes a white noise begins to emit from the right channel. It does not matter what the input source is and does not vary with volume. If the volume is turned all the way down it is still present. It gets continually louder until it's necessary to turn off the receiver fearing danger to my speakers. It sounds just like the white snow on an old tv when it's between channels. If I hit the receiver lightly with my fist then there is a pop and the hum disappears. It returns slowly and builds up until I tap on the case several times and it disappears for quite a while. This problem was present prior to replacing the large filter caps that corrected the distortion. Strangely, if I tap directly on one of the filter caps it crackles and the sound goes away just like hitting the case. But, tapped elsewhere there is no improvement.
I am thinking that there's a failing solder connection and this unit has been messed with before and there are visible fresh solder areas.
My question is two-fold.
1. Are there certain parts that characteristically cause a loud "white noise" sound like this that would correct when tapped?
2. In an effort to isolate the area of the receiver at fault I am thinking of swapping the internal wires that run to the amplifier board P600. There is a left channel, right channel, and common ground that is exposed and easily swapped to see if the sound changes side to narrow down to the preamp or amplifier sections. Is there any reason that would be a bad idea?
I am new at getting this deep into repair and self-teaching which is why I bought this receiver.

Thank you in advance for any assistance,

Bill

 

[Blubau]

I'll answer my own thread that may assist another user.
I found a bad solder joint on a transistor in the P400 tone and preamp board. Good as new now.

 

[Skywatcher]

I'll answer my own thread that may assist another user.
I found a bad solder joint on a transistor in the P400 tone and preamp board. Good as new now.

I missed this thread completely. I recently rebuilt a 22 and there were a couple of bad solder joints in it as well, but were on driver transistors. On those, it actually blew the transistors. Those tall heat sinks on the TO-5 transistors didn't help. There were a lot of revisions on the 22, and after a certain serial number they become the "22r" with all the previous service bulletins installed from the factory, including an updated transformer. However there is no "r" anywhere in the model number. Glad you figured it out.