A sloppy gearchange is a common fault on the Mk1 Golf and its variants. Luckily, the parts are inexpensive and readily available to solve this. With thanks to "JSeaman", here is an article describing how to replace the gear change linkage.
First, apologies - I ended up doing this in stages over several weeks so this might not string together too well. Hopefully it will be enough for you to follow. When doing a shift bushing rebuild, it's worth spending the extra £10 ish on doing the ball assembly too.
You don't have to do this but it seems silly to have it all stripped down and only do the basic bushes. I recommend the proper kits either way because they are pretty comprehensive (unlike the ebay ones) and are cheap too.
Make sure you get mk1 bush kits because the mk2 kits are slightly different. The bushes alone are about £5 to do whereas the kit with the base of the gearstick is more like £15. Money well spent and can restore your gear feel completely, especially if you are having trouble engaging gears and slipping into reverse instead of first etc. My car couldn't get fifth at all, first was almost impossible and generally it was awful, the linkage gave me all five gears and a much (much) firmer shift.
1. Gain access to the base of the gear stick. Unfortunately I didn't have any of the trim on here so can't tell you how! Once you've got to the bracket and bolts shown in the picture, remove the 2 bolts holding the plate down.
2. Jack the car up as high as you can, the higher you get it the easier this job is (use axle stands).
3. Looking up near the front of the linkage you will find the shaft from the gear lever ends in a box/ball mechanism. Remove the 13mm pinch bolt that holds the rod in place.
4. Now the selector rod should be able to slide out and be completely free at the front.
5. Now look up to the other end of the shaft (where it meets the gear stick) and you should find a rubber housing of some kind. Again, I didn't have this so can't tell you any more than that! Remove it to gain access.
6. Using a 10mm spanner and a 13mm spanner, remove the bolt holding the linkage and bushes together.