we have a set mate that were bought secondhand last year for £325 and used on 2 track nights. I had to give them a good clean up and bought new spring platforms for them from GAZ. on the back, the settings seemed odd in the way that one was set higher than the other but it was level if that makes sense? anyway, worked well so i never looked into it further, possibly a recon or service from GAZ would benefit them.
Dave, Gaz do a good recon service, about 25 quid a corner, and all done in a couple of days. Also I have some brand new Gaz springs going spare, IIRC 800s for the front and 700s for the back, should you need them.