I had a similar problem on Avalon B36, and after talking with sureflo tracked the problem down to the seal kit on the pump.
Their contact details are:-
Leisure Accessories Ltd
Britannia Works,
Hurricane Way,
Airport Industrial Estate,
Norwich,
Norfolk,
NR6 6EY
UK
Tel: +44 (0)1603 414551
If you ask for tech support they’ll help you diagnose the problem and ship any relevant parts for next day delivery.
Hope this helps
Cheers
Jim
