After looking around the internet for advice, I decided that the minimum I would need was a wear kit, replacing all the bits that generally wore out. So I drive to Woolverstone Marina Tuesday lunchtime to see the guys a Volspec, Volvo marine engine specialists. Apparently the pump has changed a number of times of the years so best to check which one I have.
Wednesday I take the afternoon off and go to Capella and remove the pump and dismantle it on the table (tip – keep a few cheap sandwich boxes on board to collect the bits). One look and I se the back plate is badly scored. This is an old version of the pump and has no wear place at the back, the scoring is in the brass casting. I head back to Volspec expecting the worst – yup a new water-pump at £211 – they will have to order it in should arrive Friday.