Over the covid period Lurch has not moved. The front left corner sank quite quickly and, when started up, the suspension didn’t respond.
A new strut with bag was fitted and a new piston ring was put in the compressor which got it back up, but it took ages. IID showed the air reservoir was only achieving 92psi with pump temperature of 120 degrees C. Knackered pump then.
I bought a new cylinder kit from Bagpiping Andy on Ebay, £70 being cheaper than £650 for a complete new compressor/dryer. Excellent kit.
I stripped the dryer and cleaned the filters including the sintered bronze intake, fitted another piston ring (Andys appears better than the first one) and put it all back together.
I now have 196psi with a pump temperature of 48 degrees max and a fully working system. Hurrah!
By the way, the compressor big end felt a bit rumbly, no play yet though. I put a few drops of oil on the bearing oil seal edge as I could see a tiny gap. It worked in and improved things no end. I can’t trust it long term that so a new rod and piston is next (unless I can change the bearing) along with replacing the other three bags.
Conclusion - if your pump is on the blink check the bore very carefully, especially at TDC. If it isn’t perfect get a new one. Use the opportunity to clean or replace all the filters. Same applies to the con rod big end bearing, if in doubt change it.
I see no reason why this pump won’t last another fifteen years for less than £100.

I can’t find an EBay user called “Bagpiping Andy”. Does he have a different username? Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

Try bagpipingandy
Does that work?

One last point to consider is that the intake filter. It was dirty and probably quite clogged. As I can’t tell how clean it is I’ll cut a tee-piece into the 6mm (?) pipe and fit an additional replaceable small filter to ensure the pump can breathe freely.

Found him, thanks.

Sadly it’s for the older version of the pump, up to 2005. Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

balls. I was hoping this was for the Hitachi pump.