Vw golf mark 2 1.8 gti 16v is hard to get in to 2nd and 4th

Sounds like you will need new shifter links, there are only available from a VW dealer and easy to install. There are two of them, they are usually white (when not covered in dirt) and plastic. They snap into place on to the metal rods for your sifter linkage (located on the back of the trany by the fire wall) when these get worn badly it makes it hard to shift into certain gears not all gears tho. A good indentation that these are worn out is a sloppy shifter. Also the linkage should be lubed up to make it easier to shift, if your shifter is not sloppy then try lubing up each link (think there is 6 pivot points) even the main slide link. Let me know if that helps.

vdubs 4-ever