tracking issues

I recently took pity on a friend with car trouble and let him use my golf for a couple of weeks, on its return it really liked going left, on its own. Naturally I quizzed him regarding pot holes and curbs and he swears blind he didn't meet any en route.

I have since changed the nsf lower arm and had it tracked up, which fixed the issue f.or about 5miles, now it likes left again. given my understanding that track can only be adjusted osf and it needed to be turned out quite some way I'm stumped. there is probably not a lot of adjustment left.

camber and caster were set to within the tolerance, they were a little out, I'm now considering the steering rack to be at fault.

Does this seem likely, how do I check if it is and how bigger s**t of a job is it to change it, they seem reasonably priced.

the rack mount welding points are known to go on mk1, so start there. might be the bushes are worn/loose and the rack is moving so look at that too.

apart from that check all the wishbone and balljoint bolts are tight