Hi,
I appreciate that this is an old thread but!!!!
Most of the Hydramax range are made by Aqualisa. I use here for spares:
http://www.shower-warehouse.co.uk/erol.html#1058X0
Hydramax can be contacted at:
The flyers Way
Westerham,
Kent
TN16 1DE
01959 560010
Regards
Paul