There are several problems which can prevent an Aries from working properly.
The most common problem is the servo rudder shaft experiencing too much friction when it tries to rotate. Through the gear system at the top of the rudder shaft the airvane is supposed to rotate the servo paddle slightly to port or starboard when it flops over. If there is too much friction in the plastic bushings that are at the top and bottom of the pendulum casting the airvane will not be able to do this, especially in light air. If you take the servo rudder off the unit, or at least fold it up, the airvane should return to an upright position if you push it over to one side. Note, however, that the counterweight is offset to one side so there is not equal rigthing force in both directions so the airvane may not fully return from one side. You want the least amount of friction on the rudder shaft as possible. The only way to correct this is to dismantle the unit and replace the plastic bushings. I replaced mine with bronze bushings and these work great.
If someone has dismantled the unit another possible problem is a misalignment of the servo rudder when the airvane is vertical. With the airvane in the vertical position the servo rudder should be aligned exactly fore and aft. If the gears at the top have not been meshed correctly the servo rudder will be slightly rotated either to port or starboard. This will cause it to flip up to one side or the other when the boat is in motion.
A less likely problem is installing the servo rudder facing the wrong way. The leading edge of the rudder (where the shaft enters) should be forward.
Lastly, an airvane that is too heavy can make the counterweight ineffective
My vane is a three layer mahogany laminate 5mm thick. It is about 115mm long, 22mm wide at the base and 18mm at the top. No paint
. Seems to work fine in moderate winds. Have not really tried in very light air.
When using the Aries you get the boat on course, align the leading edge of the airvane (edge with counterweight) into the wind so that it stands vertical and then engage the steering
lines. It helps to get as much slack as possible out of the steering
lines as the servo pendulum only has about six inches of travel to either side and you don't want any of this just taking up slack.
Hope this helps.