I have done a 'drop test' by pulling one of the ESC fuses (I went for fuse 35 on the inside). It may not have been the best fuse but it did let me know that the front drops significantly more than the rear and the passenger side slightly more than the drivers side.
I have been squirting washing up liquid around the joins and struts but have not found anything yet.
I did find out that I have a new compressor (an AMK 102391) I do not know if this is a good thing, but it is one less component that could have needed replacing.
I'm currently having lunch, but I'm about to go and have a look at the front valve block next.

