Ineed cleaning instructions as I have lost the

This link should open the manual for you. I covers both the frog (the model you have) as well as many others. http://cache.air-n-water.com/manuals/crane-ee-3191.pdf

Instruction manual: http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

http://www.crane-usa.com/manuals/HumidifierManual2008.pdf
This is the manual for all "adorable" crane humidifiers.

Cleaning instructions are in the manual. They are posted online here Link to Manual:
http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

Fan problem is most common. Make sure the unit is not on carpet, blanket or has paper etc blocking the bottom. Second cause could be the nebulizer has gotten dirty. See the instruction manual for how to clean this.

Link to Manual:
http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

Changing the water does not clean it. Please see the instructions for how to clean it, they are online at Link to Manual: pg 9 if I remember right.
http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

Link to Manual online:
http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

I don't think you would have to clean it weekly, for me every other week or once a month works, but our water is pretty low on minerals and bacteria.

FROM TROUBLESHOOTING SECTION OF MANUAL:
Humidifier power light is staying red and not turning green Humidifier is working than stops: ? Ensure that water level sensor is assembled properly. ? Clean water float ? Call service center and request replacement water float

Link to Manual:
http://www.crane-usa.com/manuals/HumidifierManual2008.pdf

Filters can get dirty pretty quick with the use of tap water. I attached the manual for you so that you can clean it.
Personally, i replace my humidifier filter at least once every 2 months.

Good Luck.

PDF Manual for Crane frog humidifier: http://www.crane-usa.com/manuals/AdorableHumidifierManual2007.pdf