Gear shift

I have an /89 Volkswagon Fox GL. It has 154,000 Kilometers on it.
For the past month it has been very hard to get it to go into first gear. In the past week, I have found that it will only shift into first on initial take off.
There is nothing wrong with the clutch, however, I feel that something in the mechanism under the gear shift itself has shifted. I've taken the boot off, and the protective housing and taken a cursory look.
What I need to know is how big a job it is to make the necessary adjustment myself and what I should order from my local dealer before I take on the challenge. I need to say that this is one car that won't go to a shop if I can help it. I've already replaced the alternator and 2 V-belts on my own, and installed a radio, plus replaced part of the neopreme gas line on my own. I realise that starting out in second gear will eventually have an adverse affect on the clutch which is why I'd like to get some insight as to what I should do about the shifter. Thank you.