Do you have a cunning plan of how to preserve the current tracking setting?

The yellow vacuum tube goes to a thermac switch (valve) in the air filter box. There should be another (probably red) coming from the other side of that vacuum switch, then going to a nipple on the inlet manifold. The vacuum from that switch operates an actuator at the air inlet, to draw warmed air ...

Have a look at this thread: https://rover200.org.uk/forums/topic/16491

Is there a SU carburettor factor involved?

I like this positive view of the Honda relationships prospects, and it does tie in nicely to BAe being the ultimate villains. After all, a lot of the mess BMW inherited was a result of BAe's underinvestment previously. I tend to home in on George Simpson specifically. Although he came from Leyland ...

I'm in a similar position with my 1991 3dr 214S.

When you become a Club member, you can access this page to qualify for a discount:

https://rover200.org.uk/members-login/m ... panels-r81

I recognised JZX as a prefix from various A-R carburettor parts and other fuel system components.
So it's appropriate that Burlen list them as in stock, as Burlen now looks after SU carburettors.

https://sucarb.co.uk/potentiometer-2.html

Been a while since I had mine (from a R8) apart to fix a non-closing flap, but recall it was marked 'Valeo' on the casting. If yours is similar, and particularly if the key blanks are listed as common to the MG's that I'd say they're likely enough to be the same component to make it worth your while...

A good start would be to locate the heater control valve, and check that its operating
lever travels reasonably freely over its complete sweep.

A story I took notice of at the time was that GKN Driveline was aggressively bought out by a
vulture capitalist outfit a few years ago. They're unlikely to give a toss about maintaining
quality over short-term profit.