S40 Gear problems getting into 1st 2nd and Reverse

I have a '97 Volvo S40 and I am having a lot of problems getting it to go into 1st, 2nd and reverse gears. I can get into first by lifting the reverse latch and putting the gearstick through the motion of going into reverse. Getting into reverse is very difficult, it requires a fair bit of force and it feels as if it is further over to the left than it should. It almost feels like there is a guiding plate which has slipped slightly to the left and that is why I am having difficulty changing gears. Does anybody know if this is a big job? Or can I do it myself? Many Thanks Allan