Baxterdown,

Edit your topic . It's a 300 SEL not 280 SEL...."New W109 - 1971 280SEL 3.5 Questions" .

As for the air suspension dropping, it needs proper diagnosing. It could be the front valves or the lines or the fittings on the lines or the bags themselves or a combination of all of them leaking. I have just gone through this same type of issue. Welcome to the air suspension blues club. But once sorted, you'll not need to concern yourself with it for a while. I've just spent a bundle on valves and bags etc....

I'm just about to do the heater levers in mine . I found this thread with the link included in it very helpful .

W109 300 SEL Heater Lever Replacement - Mercedes-Benz Forum

Congrats on the purchase !