Gentlemen: To more mundane matters.
The parking brake cable on the 73 XJ6 slips off the sheave in the engine compartment when pulled hard. The cable comes out of the firewall and then makes an almost 180-degree turn by means of the sheave and travels towards the back of the car. Is there something missing that perhaps covers the sheave to prevent the cable from slipping off it?
I checked the 71 XJ6 but that is a totally different setup. In that car, the cable pulls a metal arm that pivots and probably connects to another cable under the passenger compartment.