Help, new to caravanning, just bought a Compass Rallye 460/2 GTE which has a Carver Crystal Water System, (for shower etc) however the chap who sold it stripped it bare of equipment and won't give me the water pump, the manual states it requires a Thames Water Pump part number L230231 but all of the camping sites seem to talk about Crystal Mk 2 and Mk 3 I assume mine is a Mk 1 and I have sourced a Thames Pump but the part number is 605768, is this the same, will it fit etc? help also where can I get new filter cartridges? Thanks J