Welcome to Iboats SpareChange. There's probably several possibilities. I had this problem when I first got my (at that time) 30 year old Starcraft Mercruiser MC-1 I/O. I found that the inner rod at the outdrive connection in my rack & pinion steering cable was bent. It would extend OK but trying to draw it back into the outer sheath was struggle. So I could easily turn to starboard but not to port. I managed to straighten the rod by removing it so I could apply some brute force and checking with a straight edge. - Grandad
Is it possible the trim tab fell off, or is loose and not doing it's job? The trim tab is a rudder looking thing hanging off the drive usually behind the prop. It gets adjusted to help fight the torque steer effect from the spinning prop. If it falls off you get the symptoms you described.
Volvo penta 5.0 GL volvo xl drive. I did replace the prop with a rebuilt one I got from previous owner. I'm not sure about the location of the trim tab or if it's still there.
