Bongo Fury

Hello everyone, i have a slight diesel fuel leak from the dome area of the pump (suspect usual area). I have read a few threads and the official PDF about how to change these seals insitu. I'm not sure its something i want to try myself now after just speaking to a listed Bongo friendly garage in York where i live. They have said when they tried it before they had issue of the pump getting out of calibration and they advised to have the pump removed and sent off. Is this a common thing or are there other garages which have undertaken this easier repair?

Any advice would be great, its not leaking much but i know its not going to fix itself.