Trying to find faulty connection

Just been handed a Sony reel to reel tape deck to repair. Somewhere theres a dodgy connection as when the circuit board is moved the sound goes on and off. Whats the easiest way to track it down?

Si

By tracing the signal, and finding where it's disappearing.

A very common fault with tape recorders is the record/play switch, it could be as simple as that is dirty or worn - try gently moving the switch and see if that causes the fault.

Thanks Nigel! Recently got an oscilloscope and this could be my first job with it!