Yes Sirfixalot, there is a bit on the net.
I have not pursued with lock down, also the C5 is small enough, bit dear and also prone to breakdown. Also Merc & BMW are small but I cant afford the 24ct Gold they are made out of (2nd hand complete units).
It always fasinates me as to why a quality company makes a quality high performance product and includes rubbish third party equipment that because of their location or function become the bane of owners. These minor systems cause an undue amount of bad feedback which reflects badly on the vehicle and therefore G.M.
OH! And to top it off, they either discontinue holding spares or the 3rd party supplier goes bust or as in this case is taken over, moves State, and doesnt want to know about previous issues - all they wanted was the trading name.
The ridiculous part is, there are thousands of C4's & C5's out there with buggered seat lumbar pumps, all would be very happy to purchase replacement parts - looks like an opportunity going begging. You can probably tell from my tone that the pain killers have not kicked in yet.