So… this is a fun one - an upright electric piano:
We’ve had this a long time, and it was an inheritance when we got it. It’s ooooold.
Recently the volume has started to vary by itself, sometimes quieter than it should be, sometimes louder. Seems unstable, I guess the amp is probably failing? Also one of the keys is dead.
Obviously a bit big to bring to the Repair Cafe… Am in in specialist territory here?
The dead key is probably a dodgy contact.
The volume variation could be one of several things. If it’s a valve amp it could be a valve breaking down. It could be a dodgy wire connection or a dry joint. It may even be a component breaking down.
It may be worth tapping around the circuit board to see if that changes the fault.
Hmm
Never seen one of those before. Perhaps replace all the electrolytic capacitors, if it has them.
If the volume is a dial or slider, it could be a dirty/warm potentiometer.
Think we have a bag of sliders just in case you need one.
Thanks for the ideas folks.
They are sliders, yes. I assume I’ll need to get into the control panel to check this?
There’s not a lot of room to work in that part of the house, so I’ll have to figure out some time to move things around 
Yeah. If it’s the slider, will need to check to see how the voltage changes as the slider is moved.l and see how stable the value is when left alone.
Thinking about it, might be easier to test when on and hooking up a scope. Can plot the voltage over time and see how it looks when sliding the slider.
