Ernemann Er-nox camera

This really is a very straightforward and direct question, so please respond similarly. Off beat and and round about ("depends on...") responses are not appreciated.

Now, I recently acquired a 1924 Ernemann Er-nox plate camera (Ermanox - Camera-wiki.org - The free camera encyclopedia) that I might on sell. The question I like to put forward is this, "With these types of vintage cameras, it is worthwhile and profitable to get things like the shutter mechanism/curtains repaired or the lenses cleaned? Would such actions appreciably enhance the value (relative to revamping costs) of the camera or not? or is it more of a sink hole like some cars and boats?

Antique plate cameras are a niche market with less predictable rules. As john_shriver indicated, most collectors will just display, so may not care so much about it actually working (of course working is always preferable for anything). If you have a tech friend who repairs these that can give you a steep insider discount, it might be worthwhile as the buyer appeal of "freshly serviced" will not be nullified by a too-much higher asking price.

But as a general rule, its almost never worth it to pay camera service costs before selling: they're difficult to impossible to recoup. Except in the case of extraordinarily in-demand cameras (Leica M, Rolleiflex) known to have very few good repair techs with very long wait lists, most potential buyers are either looking for bargains or are more inflexible about values than you'd imagine. Almost every single camera or lens you can think of has an absolute price ceiling beyond which few are willing to pay, overhaul or no overhaul.

Everyone is looking for "fully functional at the going rate or less". This applies even when something serviced is actually the far better choice, i.e. a Hasselblad lens that normally sells as a gamble for $400 is well worth $700 with proof of recent service by David Odess, yet you can whistle up a rope before you'll find a buyer willing to shell out the $700 for a flawlessly serviced example. They want it for the same $400 all the other randoms are currently selling at (despite that fact it will almost certainly break down within the year requiring a $300 to $400 service anyway).