I am starting to have problems with the power steering on my '89 740 Turbo Wagon. I am used to the relatively heavy steering that is typical of the Volvo; it's going beyond that. I am finding that turning the wheel in and out of turns is becoming more and more difficult. It also seems that there are certain 'difficult spots' while I turn: for example, assuming that the wheel is at 12 o'clock and I need to turn it all the way to 9 o'clock, I feel resistance at 3 o'clock and maybe 7 o'clock more than at the other positions.

Power steering fluid is not the issue - I checked the tank (not anything else though) and it's nice and filled. What's my next point to check? Anyone know of any guides, FAQs with/without pictures that I can review?

Any help would be greatly appreciated - I am scared this wheel may lock up on me while I drive!