Replacing diesel pump suction valve

[PaulC5]

I am going to replace the C5 (2.2 hdi 2007) diesel pump suction valve to see if it helps the rough tickover when warming up. Has anyone done this, and if so is a lot of diesel is spilt when removing the old one. Also is there a gasket/seal where the valve is fastened to the pump and if so can the old one be reused ? I have a valve from PF Jones at reasonable cost so is worth a try since a diagnostic at Citroen did not find anything, fortunately they did not charge being one of their long term customers.

[PaulC5]

I found a pump parts diagram (Bosch pump 0445010139) and there is a gasket between the pump body and suction valve. Pictures of the gasket look to be rubber so the old one might be able to be reused, Part no. Bosch F 01M 100 055, Citroen part 1933.52.