Our Hayter Harrier 41 is regularly serviced by me and has had new belts for both the cutter drive and the gearbox drive.  If the Varispeed control is advanced to anything more than a slow walking pace the machine makes a loud rattling noise as if something is striking the frame/deck.  I have removed/dismantled/cleaned the pulley Variator assembly [411001] but this has made no difference.  I did note that the pulley sections did not slide very easily on the splined shaft.

I would be grateful for any guidance as it will only be a few weeks before the Head Gardener needs the grass to be cut again!!

Jim