Cheers for the comments (even you Rhys) 
I think I'll be going for a K04-001 

Bit of repair work carried out over Xmas, I've been putting off fitting the new seat base for ages now so thought I'd better do it before the material wears away and ends up costing a lot more
no pics of during as it was a complete arse of a job but this is the state of the base I pulled out


Totally knackered 

new one feels lovely now but it's not a job I want to do again lol