When turning at low engine speeds or with clutch it I get a shake in my steering wheel. I am thinking my power steering belt may be loose. I have not heard and squealing. Is this the most likely cause of the problem. It feels like the power in the power steering is comming and going. I had an issue once where i lost all power steering because of a leak in one of the connections. That time it went from normal feeling to no power in about twenty minutes. This time it has been weird for about two weeks with out getting worse.
sounds like another leak/low on fluid. Aeration of the fluid will cause that. Also fluid that is not up to the task (old fluid, or new thats SHITTY) will cause that. It takes standard Dextron 3/4/5 ATF. The 5AT HP-ATF works wonders in there too.
The leak happened about a year ago after the one and only time I paid for an oil change. It was actually the next day so I went back to the jiffy lube or whatever and asked if they could have mess with something. They found the leak and tightened the fitting. Since I was totally out of fluid they replaced for free. I'm not sure what they used but it is only a year old and has not had issues until recently. I will check the fluid level and if it persists drain and put in some better stuff.
They likely put 'power steering fluid' back in. Same but different. the subaru system does not like normal PSF and it will degrade after a 'short' time. The ATF in there will last 8~15 years before showing signs of being done. Unless you autox/roadcourse in which case you'll see it quitting after a few months or less. The standard PSF will not even put up to a track day/autox in a subaru system.