Heathkit AA-15 integrated amplifier

Front view. I've got this amplifier like this a long time ago... without it's wood cabinet. It's powering up but haven't tried it with speakers. A cleanup of contacts is certainly due. Heathkit are very good audio systems.
Heathkit AA-15 integrated amplifier

Inner view

-Origin: USA
-Year(s):1968
-MSRP: N/A
-Power output: 50 Watts RMS/channel 8ohms, THD: N/A
-Frequency response: n/a
-Consum: N/A
-Preamp controls: Bass - Treble - Balance
-Selector: Tuner - Phono - Tape - Aux
-Buttons: Tape Monitor - Mono - Loudness - Tone flat
-Speakers selection: Main & remote (2 pairs)
-Extra informations: Phones Jack
-Dimension: 16 7/8"W X 4 3/4"H X 12 3/4"D (as is)
-Case: Front: solid aluminium - Cover: Missing
-Weight:
-Status: in hand.