Hello, we sell a diaphragm pack with a spring for Macdee Metro syphons. You can find this here :http://www.ebay.co.uk/itm/DERWENT-MACDEE-SYPHON-DIAPHRAGM-WASHER-METRO-SIPHON-CISTERN-SERVICE-PACK-SPRING-/201186987297?pt=LH_DefaultDomain_3&hash=item2ed7adcd21
Hope this helps
Steve
April 2015
as far as i know you can not, the whole cyphon will need to be purchased or you could by a similar cyphon and take the parts you need.
if you need some on to fit it check out
http://www.emergency-plumber.eu/
or
http://www.freeindex.co.uk/profile%28emergency-plumber%29_627996.htm