LUXMAN 117 Help Please II

I am still having problems with a vintage Luxman 117, but narrowed down the issue with one channel dropping out . From what I can see with a flashlight there is a separate board that the RCA inputs are connected and thinking there is lose connection, or cracked around the RCA because with a push - it moves slightly [down] and the sound returns.
Question, has anyone removed the far rear circuit board on a Luxman M-117?
 
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