Lude Generation

We bought a BB1 today. One of its snags is that the heater doesn't seem to switch off on the slider, although the mechanism feels OK. I haven't had time to look at the thing yet (too dark), and a forum search hasn't shown up much, but is this common? What's the usual cure?

I've had the mechanism that adjusts the flow to the heater matrix seize on another car. I'm not sure how visible it is on UKDM's but can you pop the bonnet and get a second person to move the slider whilst you watch the pulley? Sounds like it's stuck open.

Congrats on the purchase.

No help whatsoever on the answer, sorry.

All the heater adjustment stuff is inside the cabin on 4th gens, not under the bonnet.

That's not a common problem no, but I'd be thinking it's something like the adjustment cable come off the mixer valve?

Thanks for the tips, chaps.
I've had valves stick and cables come off on BMC cars, but not on Hondas. Will give it a go tomorrow if I get the chance.