Shower Mixer Tap Lever Won't Budge

[DSA]

Hi,

We have a (fairly ancient, yet authentic) shower mixer tap on the bath with a stuck lever arm to divert water to the shower head (luckily stuck in the Shower off position!)

Is this likely to be easy/?possible to loosen, or should I just replace the whole mixer tap? The latter option seems a bit extreme and costly, but I am asking here as you probably see this all the time and could save me a few hours fiddling!

Thanks.

 

[Softus]

Dismantle diverter valve, remove scale, replace worn 'O' rings, lubricate with silicone grease, reassemble, test.

 

[DSA]

Do I need to turn the water off at the mains to take the diverter valve apart, or is the fact that the taps are off sufficient?

 

[Softus]

The diverter is downstream of the taps, so it's sufficient for the taps to be off.