On Wed, 4 Nov 2015 14:31:09 +0000, Michael Chare wrote:

Any suggestion as to how I might remove these plastic disks without
damaging the handle or the disk. The disks have been there for some time
so no doubt held in place by a little grime.

Clean the tops well and leave a damp cloth over them for a few hours,
if your water is hard soak with dilute lime scale remover. Look
carefully for a recess along the edge of the cap into which insert a
small bluntish flat blade screwdriver.

--
Cheers
Dave.