leaking pipe feed

[refresh]

Hi, we have an old shower system, gainsborough 400. To use it we have to turn one valve to let water through and then press another button on shower unit to start the actual shower.

Whenever the valve is turned on so we can use the shower it leaks cold water like a slow running tap from the valve.

The valve has a plastic cover I tried to remove but it's not coming off easy and now I'm worried if I take it off water is going to shoot across the bathroom.

Could you let me know how to go about fixing it please?

Thanks

 

[Bahco]

Can you change the valve for one of THESE

 

[refresh]

Well I hope so, will visit DIY store tomorrow and see what I can find. Cheers.