You could try e-mailing the manufacturers and ask them if they have a copy. Also there is a newspaper called the Sunday Post up here that has a weekly column for people who want to track something down eg: out of print books, instruction manuals, knitting patterns, anything, just ask...
You can email them at
[email protected] giving details of what you require with the make and model of your slow cooker and leave your name and address. You'll be surprised how many people will help if they can and often at no cost. Yearsago my mother appealed for an out of print cookbook and received 6 through the post. Not one person requested the postage. Also a friend of mine broke the sugar bowl of a discontinued tea service and she too received half a dozen replies. This is probably your best bet. In fac I've just remembered I've mislaid the instruction book for my food processor so i think I'll go and take my own advice. Good luck!