Vintage Hammond organ. Circa 1967. This is an all tube Hammond organ. Four keys do not make a sound and two keys stick. I'm not sure, as i am not a keyboard player but the above mentioned might be an easy fix, otherwise all the different instrument replication paddle switches, volume control knob, reverb, percussion, vibrato, and the volume pedal all work well. I've owned this Hammond organ for over 15 years but need to sell it now because i am downsizing.