Bath Shower Mixer Stiff

[Purple_Popple]

Hi Everyone,
I have increasing trouble trying to pull up the *** on my bath mixer tap so that the water is re-directed to the shower head, it's making my fingers sore, I have tried spraying lubricant all over it and unscrewing the *** itself off and spraying the bits underneath but with no avail, the picture shows the offending item.
Any other suggestions to loosen this and make it smoother & easier to pull up ? Media URL: http://www.bathshop321.com/images/photos/1608/tavistock-index-bath-shower-mixer-tap_MA.jpg
Description:

[Purple_Popple]

http://www.bathshop321.com/images/photos/1608/tavistock-index-bath-shower-mixer-tap_MA.jpg

[WILLWONKER]

Get some WD40, and spray some on for the next 2 days.

[The Builder]

The problem is most likely down in the valve assembly itself, Popple.
Once the head is removed (the bit you pull), there should be a way of dismantling it.

They're pretty simple. It's probably just a sliding bit that travels between two ports.... one for the taps, and one for the shower.

Dismantling may be from the top or underneath, where the hose connects.

It's a matter of figuring how to take it apart. Once you have, it's only a matter of greasing the rubber O-rings. Silicone grease, or even Vaseline will help it to slide more easily.

That's your challenge ... how to take the valve apart.

[Purple_Popple]

Thank you all who have answered ! :)