4-Wheel Drive Not Engaging

The 4-Wheel Drive on my 1997 Tacoma 2.7 Liter is not engaging. It is a 5-speed manual with a physical stick lever that engages the 4x4. (It is not an electric push button engager). When I pull the lever into 4 Hi or 4 Lo nothing happens (the green 4x4 indicator light on the gauge cluster does not illuminate either). I checked the 4x4 fuse in the cabin and it appears to be good). I jacked the truck up on stands so all four wheels could freely spin and while idling the engine in first gear I engaged the 4x4, but only the rear wheels moved. While 4-wheel drive was engaged I could see that the short drive shaft from the transfer case to the front differential was spinning, but neither front half shaft axles from the output of the front differential to the front wheels moved. So, the problem appears to be isolated to the front differential. Is this perhaps an actuator in the front differential? Let me know where you think I should start troubleshooting from here.

 

It more than likely the actuator on the front differential.
Not always, but usually.

 

I thought the early models didn't have an actuator. Are your hubs unlocked?

 

The truck has auto-locking front hubs.

 

Is the vacuum tube going to the actuator still intact?