Lucas Pi throttle bodies

[tapkaJohnD]

Lucas Pi fuel injection uses twin throat throttle bodies, with a butterfly in each, mounted on one shaft.
The shaft is brass (coloured, anyway) and runs in drillings in the aluminium alloy bodies.

Twice now, I've had the front body butterflies seize wide open, which of course locks the other four ditto.
Both times it was the central drilling, between the throats.
Not nice, scary, even if the problem is solvable by turning off the ignition.

I just changed the butterfly shaft the first time, but this time, I want to do something to prevent this happening again.
Bushes in the body drillings? What material? Suppliers?

Glad for ideas.
JOhn