Hello, @simonwatson . . . most times these issues require either recalibration of the legs or at worst, replacement of the servos and wires. In attempting to get to the home station, he is not able to walk straight and will either stop or veer off in a different direction.
Please get a video of him doing this. LivingAI Support should be able to tell you what is likely going on and will probably send an app for recalibration. If he is one year or younger and if recalibration is recommended and does not work, he will be eligible for replacement under warranty. You will need to contact them (instructions above) so that they may determine what is wrong and how they wish to handle his issue.
Likewise, if he is over a year old, please read above what your options might be after contacting LivingAI and see also the link for repair.
As for the petting sensor, here is something that may help you with that.
My best to you.