Jacked the Irmy Elite up today to have a rummage around underneath...
Established that the SL doesn't work even when manually activated, not surprising really given that the rear shocks came off in four pieces

So SL removed, along with springs and shock remnants, and replaced with Irmscher items... doesn't seem any lower, but then it probably wouldn't if the shocks were toast

Need to collect a few bits to renew the rear top mounts and rebuild the front suspension to taste.
Discovered the following additional issues...
Rear calipers have been replaced recently, non vented ones along with non vented discs

Has had a complete new exhaust recently... cat pipes look to be a bigger bore than standard ones, will take a few pics when next under it... but whoever fitted the exhaust managed to cross the centre pipes to the back box, so they run vertically rather than horizontally next to each other, a side effect being that the right hand centre box has split all its hangers

Diff is a bit of a mess, leaky pinion seal, but otherwise it pretty good shape underneath, so sorry Joff, but those bumpers are staying
