Heatline viso 24 plus pump fault?

I have just installed a heatline 24 viso plus boiler.(Its out of guarentee because I have taken it to spain and its been sitting for 18months until I could fit it) The pump is noisy ( humming). When I put an avo across the pump it reads 60v when the pump is supposed to be off. Boiler runs ok but obviously the drive circuitry for the pump is faulty ( some sort of thyristor drive I expect) - does anybody know where I can get a circuit diagram for the board. Or does anybody know of a fix.