I had refilling valves fitted to the two front spheres on Tuesday. They were filled to 55 bar. What a difference! My BX has it's smooth ride back again. All the 5 spheres were new in October 2003 but are dated around a year before that so I guess the next thing will be to get sphere valves fitted to the rears and accumulator. I suspect that the accumulator has lost some pressure as the regulator ticks are a bit more frequent than when it was fitted 16 months ago so that will be the next one to be refilled.
My Citroen expert recommends refilling every 2 years - Only $17.50 as against $150 each for new spheres.