My 2 cents,
I obtained an electric wheelchair motor for $50 (Cdn) and attached a 3" sprocket.
The motor is very much like a boston gear 90deg reduction gear motor only in 12 or 24vdc.
I then literally wrapped a matching chain around the chute attaching it to a welded anchor point that had 2 holes drilled to accept the chain ends.
This bracket or tab I located such that I could get my desired left /right limits, ie with chute blowing about 30 deg fwd on left side when the tab was at near travel limit.
I also used a threaded rod (short bolt) to serve as an adjuster.
I ran this setup all last winter with no problems at all.
The wheel chair motor is a worm gear drive rig designed for slow speed and oodles of torque.
I found that with the chute (chain and sprocket) all iced up there was enough power to break it loose easily.
Up here folks also use these drive motors to roll/retract dump truck tarps as well.
Being a DC motor wireing is a simple rocker switch with center off and spring loaded both sides.(DPDT)=$10.00
Total traversing from side to side is about 15-20 seconds and with a rocker switch you can place it about anywhere you wish unlike a hydraulic valve.
Oh, and over the top of the sprocket I made a 4" poly washer to prevent crap from entering the sprocket. Luckily the output shaft had a threaded hole in the end to facilitate this.