On 24 Jan, 21:51, "Bald eagle" wrote:

Manufacturers instructions for cleaning are just wipe with hot water but
this isn't shifting them. Any ideas? Thought about gently scraping with a
Stanley knife blade but don't want to make it worse.

Best thing I've found (glass halogen & ceramic, haven't tried
induction) is a metal bladed scraper sold by Partsmaster at a couple
of quid for two, maybe made/sold/approved by Creda themselves (AFAIR).
I bought it as a gimmick when ordering washing machine spares, but
it's just the job for this scraping. It's like a Stanley blade, only
thinner and more flexible, springy stainless steel with no sharp edge
other than a square, held in a little plastic gadget. You could make
your own with a bit of thin metal.

OTOH, the washing machine seal was cracked and Partsmaster are being
useless at refunding it. 8-(