Heater. Knobs - Air Directional Knob (Face, Screen, Feet)

I have just changed my blower resistor and noticed my speed knob was sticking out 10mm more than the other two.  I removed it to find the ferulle/spring clip still on the speed control spindle!  I couldn't get in with my point nose pliers but hooked it out with a scriber!  When I went to replace the knob the spring clip had come out!  After some faffing and checking the other two for orientation of the clip, (they both fell apart as I removed them as well).  Tried to replace them but the spring fell inside the heater control body....

Got a magnet and managed to retrieve the clips and tried again.  Managed to get the Speed Control on all working and the Temperature control but the Directional control won't play!!  It's as though the knob is too short even though it was working until I took it off.

Any ideas on how to resolve this?
 

The shafts on the knobs can split, To help prevent this, and to perhaps to repair a minor split in the shaft of the knob (it all sounds rather uncomfortable) put a couple of layers of heat shrink tubing over the shaft of the knob to reinforce it.
But you might be up for new knobs.

The knobs on the car are aluminium, so no danger of splitting.  It just seems when I push the knob into the hole its too short to engage with the spindle.  I will re-strip the centre consul, to see if when I reassembled it after strip down, I didn't engage the plastic screen on the front of the heater control switches correctly!

I believe there are long shafted and short shafted knobs,I don't remember which but I think it's the difference between F & TF, you may have the wrong knobs!
Possibly you might have the knobs of a Rover or some such.
Some pix would help.

Sorted! Re-stripped the heater control unit and found that the directional control spindle had lost its locking clip that holds it in place and the spindle had been forced backwards stopping any engagement with the control knob! Had a dig through my bits and pieces and found a suitable "C" clip. Installed and rebuilt all working fine.