This is the plug that is on the power pigtail. It is called a HF 6 plug.
The side that is chassis mounted is quite often the real problem as they wear are jerked around and not replaced.?
Here is a link to the pigtail connector:
Here is the link to the chassis mount part:
These parts are manufactured to the original specifications and I have used them to repair problems like you are having.
Later Japanese radios use the 4 pin connectors that have better contacts and give better service, in my opinion.
There are also plugs that look the same, but the sockets are not quite the same sizes and all of them tend to get poor connection and the resultant heat causes them to lose temper and tension.
