The GM5659-01 is an average laboratory oscilloscope that can display signals in the frequency range of 1 Hz to 1 MHz.
I bought this one in March 2006 as non-functional. The hammered metal finish case has a little rust. Some glue stains on the face plate where an inventory label used to be, reveal the outline of the letters "PTT" showing it must have been used in the PTT workshops. This means it has probably been used quite a lot. Someone has awkwardly dropped this fine instrument. The silent witnesses of that accident are the shattered mains receptacle on the back, a number of broken screws on the back, some parts of the frame that have been bent, and one of the circuit boards that is broken in two. One of the switches on the side has been removed and the switch covers on both sides are missing. These switch the deflection plates from the vertical amplifier to the input receptacles on the back, for direct deflection.
But that never happened. Shortly after this one, I acquired another GM5659 in excellent condition. A few years later, I found another GM5659 complete with visor, that was missing some parts. So this scope became donor of components. Finally, I traded it to someone who was in need of the power transformer.