Help, the Internal filter in my Juwel Record 70 has come loose. How can I fit it securely without emptying tank??. Ive lost two fish that have swam behind there and not go out. I have an Eheim external but want to keep the internal filter too if possible, rather than buy a new internal. Will silcone work underwater.?

Any advice greatly received, Presently the filter is loose in tank as I don't want to create a dangerous crevice.