Re: "Would you be interested in replacing this air system to the conventional spring system" ...
Not at all... have had this idea given many times but one automatically loses the height adjust ability that defeats a big feature of these cars...I have the height adjust on my LX470 and we use it regularly.
No suggestions as to fixing the problem other than what I gave?
How about the other questions?
As advised in my intro, all the lines & bags were checked and were fine and it was narrowed down to the valve block (one) which (as I advised) they said could not be replaced separately & the 4 would cost @$3,000+
Nothing on the other items?