Kai,
For me checking = character.
Really shouldn’t effect the price of the instrument. The right buyer will pay the right price... which is a completely ambiguous, non-committal statement. But there is truth in it. Alembics are incredibly beautiful AND extremely functional instruments (ask anyone here).
That being said some people desire a pristine, flawless finish, some don’t mind a bit of road rash, others want a specific era Alembic, or one that has been in the hands of a Master, there are so many sought after characteristics that some people will pay a “steep” price for an instrument that others wouldn’t pay a “fair” price for.
Not having the power supply would make it a hard sell for a ‘new to Alembic’ owner, those with an existing power supply would be fine.
Can you post a picture of the electronics? Some older instruments have had upgrades installed that can make them more desirable.
Good luck
Paul