My Golf MK1 not going into 5th gear

Hi everyone. I'm new here. I desperately need help diagnosing this problem. I acquired a Golf MK1 about 6 months ago. It was only ever able to go up until 4th gear. When I take the gear to the 5th slot it goes into 3rd, even though it seems to be in the 5th gear position.

I'm not sure what the problem could be, & I need to have it fixed so I can travel longer distances without worrying about damaging the engine. I'd really appreciate your help guys please. I'm only learning more about cars now as I have never owned a car before.

Thanks in advance🥲

Have a read in the technical guides on here about setting the gear linkage up.
Could also be a broken selector fork in the box

Will do. Thank you

What year, engine size and model Mk1 Golf do you have as some only ever came with a 4 speed gearbox.

Or even better post up a picture of your gearbox from inside the engine bay.