Choke knob won't stay open

[No longer active on TMGA]

The choke knob used to stay where I put it, so it was easy to start with full choke, then push it in gradually as the engine warms. Now, it starts sliding in as soon as the engine starts, which leads to awkward (and potentially dangerous), distracted efforts to pull it back out while trying to complete the checklist, or taxiing to the runway.

Anyone know how to keep the choke where it's put?

[Barry.h]

My choke appears spring loaded to open (in, deactivate). It doesn't ever want to stay out (closed, choked) which seems right to me; It is only needed for a moment when starting (perhaps it is not as cold in Australia) so it is no problem to hold it, and I much prefer the idea that it cannot be left accidentally closed (on) and will always spring open when I let go.

[Dave]

At last inspection I had to replace the choke return springs on the Bings as one was stretched out and not closing the choke properly. Thereafter, the choke control in the cockpit did not want to stay open...just as you said. Have been holding it in open position until engine warms a bit.