Tuning an electric organ keyboard
Without a schematic, here's what you can try...

Judging from the picture, your organ uses RC oscillators. When the pitch is too low, you need to use smaller capacitors or smaller resistor values.

When the group of three notes is good in itself, just offset with regard to the neighboring groups, I would try to leave the capacitors untouched, and see what happens when you add resistors in parallel to the existing ones. Let's say an existing resistor has 10&nbsp;k&Omega;. A good way to start is paralleling another resistor with 10...50 times the value of the original one, i.e. something like 220&nbsp;k&Omega;. It is very unlikely that you break something as long as your additional resistors are >&nbsp;4.7&nbsp;k&Omega;.

Trial and error might eventually lead to success...

Don't expect an organ like this to be or remain perfectly stable and expect some dirtyness even when you try your best using the pots - but that's the cool part about old instruments anyway, isn't it?