I have just picked the car back from the garage for its alignment, and
notice something unusual:

If I put my hand on the top of the steering wheel and turn it to
either 2 o'clock or 10 o'clock, and release the steering wheel, it will
roll-back to 12 o'clock automatically. But if I turn it to 3 o'clock,
and release the steering wheel, I find it never roll-back
automatically. It just keeps that position until I push the steering
wheel backward myself.

Any ideas why this happened ?

BTW, This is a 1996 volvo 850 wagon of 89K.

thank a lot  

Chun Ji