Well, it's a while since I started this thread. Some progress, some bad news, and now a request for more help.

I got some help from an aircon techie friend with diagnostic kit. The system is virtually empty. A pressure test confirms that there is a small (=slow) leak. A dye test confirms that it's not the compressor or any of the hoses/connections in the engine bay. Now for the bad news. A sniffer test reveals that the leak is somewhere behind the dash, as it picks up the leaking R12 in the driver's side footwell.

That's narrowed things down a bit. Now I need advice - and even better, some diagrams or pictures - which show
(a) where the hoses run, and especially where the joints are, under/behind the dash - since the leak is more likely to be at a joint or connection rather than inside a component of the system; and
(b) what panels and parts to remove in order to see and check the hoses, joints, and connections under there for the leak.

Why do I ask? Because I know that dismantling the dash/console etc is horribly complicated, and I don't want to mess with it any more than I have to. It would be crazy to take the whole interior apart only to find that a single hose-clip just behind a kick-panel is slightly loose! So I just want to gain enough access to see, sniff and check the most likely suspect areas. Can anyone offer help in showing me (a pic is worth a thousand words) what exactly to remove in order to pinpoint, and maybe cure, the leak?

br1anstorm