It should have a power supply with it.
When the head is plugged into the power supply and you turn on the switch, the fan in the head should start up
The lamp is intended to be controlled through an external timer. If this is a complete set up, then presumably a timer would be included. So using the timer's switches you can turn the lamp off and on.
The head should slide freely up and down the column with no binding, and the lock when it's tightened should hold the head in place.
The focusing should operate freely.
There should be no leaks in the bellows, but there will likely be some leaks at the head near the lamp, this is normal.
Alignment on these is not user adjustable, so as far as I know.
These were/are quite expensive when new, and you can see some examples of the pricing on KHB's web site.
However, the street value of a second-hand one is pretty low in comparison to what the values had been.
There are three different head configurations, the plain diffuser, a color head and a variable contrast B&W head. The modules for these are interchangable, though the color and VC modules are expensive. Of the three, the VC module is probably the most desirable, if it has just the diffusion module then you'll need to use below the lens filters for VC papers.
They are great enlargers, perhaps second only to the big Dursts.