Impeller, impeller shaft, impeller cover and o ring should really be changed every 12 to 18 months on fluval canisters. Mine tend to start rattling once they get to about a year.
Heres a link to the same maintenance kit that
@Airborne 82nd posted for UK delivery. Im finding plenty of other sellers offering the same. Any good aquarium shop should still be selling 05 parts, and if they arent they could get them in for you. Lanarkshire is a bit out in the sticks though? An hour from Glasgow?
Sealing ring a20063. Impeller flat blade a20172. Impeller cover a20156. Impeller shaft assembly a20066. Fluval 404/405 Impeller Kit. This will only fit the flat blade impeller. Oase Impeller Rotor 17965 for AquaMax Eco Premium 12000 - 16000 Genuine Spare.
www.ebay.co.uk
Edit. And no, you cant use parts from other Fluval Series filters. 04 and 05 series parts are identical, but the 06 and 07 series part arent compatible.