Update 14/7 1700hrs
Using a syringe removed brake fluid from reservoir. This exposed the floater which lifted out easily. Found some sediment around base, sides of reservoir and on the magnets of the floater which surprised me as they were quite bad. Refilled brake reservoir with fresh fluid. Checked warning light before replacing floater and its was off. Replaced floater and rechecked. Warning light does its self check and then goes OFF!! Success, thanks guys for your help.