Gearbox problem - Linkage on early car

Hi, I'm new here, having just bought a 1999 tdi 90 estate. It was described as the seller as a good runner, and as needing nothing, but since picking it up I've found that it was anything but. Anyway, this is the main issue....

I can't get reverse, putting it into the reverse position engages first gear instead, all the other gears go in ok. I've just spent a couple of hours messing with the linkage to try and find reverse. As it's an early box there isn't the easy adjustment procedure mentioned many times on here. Instead as far as I can tell the advice is to take it to a dealer as special tools are needed.

While playing around I managed to wiggle it into reverse a few times, so the gear does work. However 20 mins to find reverse each time obviously isn't practical! Does anyone have a guide that will explain the adjustment, even if it just gets me somewhere close so I can use the car?

I still have concerns that there's a gearbox problem, as after releasing both cables I couldn't get it to go in by hand. For now I'm going to assume the box is working though.

Thanks in advance