pilgrim said:
The skipping whilst turning could be the stepper motor, I think this was discussed before although the wear can occur just on one side if the motor is binding.
Good point about the stepper motor Pilgrim, though I have always suspected that there maybe two separate issues at play here - one 'dynamic' and the other 'static' i.e one being the problem with the stepper motor/software - leading to suspension wind-up and the skipping of one front wheel whilst travelling forward/back whilst on lock and the other being a more straightforward issue regarding the 'un-loading' of tension between the tyre contact patch and road surface evidenced by a loud 'knock', usually heard in the first few seconds after the steering is turned (having previously reversed on lock into a parking space and then proceeding to drive off forwards whilst changing lock).
For example - my car occasionally displays the knocking noise after parking/moving off but when driven on full lock forwards or reverse in a tight circle shows no sign of 'jumping/skipping' - consequently I do not believe my car has a stepper motor problem.
For what it's worth, I have experienced the 'knock' sound on another car (Jeep which I fitted with oversize tyres) - that car had ARB air locking diffs but even when the diff lock system was completely disengaged still demonstrated the 'knock on lock' issue but this noise only started after fitment of the oversize tyres.
Depending on what's happening with Ross's car ('knock' or 'jump/skip') the problem could be 'static' ie simply related to susp geometry whilst on lock or 'dynamic' ie stepper motor fault.
This is just my opinion/best guess - I'm not yet as intimate with the Treg's setup as other cars I've owned. Happy to defer to someone elses better knowledge.