just checked washburn site and it looks like you have a set of active bartolini customs (i imagine commisioned by washburn) here is a link
http://www.washburn.com/products/basses/xb.aspx
sorry thats for the usa model, i did a google for the model and all of them had P/J Pups in not bucker/soapbar types. they look like ok Pups tho but are likely to be active.
the only advice i can think of is to contact your local washburn dealer and ask for the info on any basses with those Pups in and if the are active get a circuit (not cheap but) to pop inside the bass.
hope you can get it sorted soon.