It seems to be the general concensus that perhaps I shouldn't do this. I don't tend to disagree. I do however have an extremely heavy, heavy duty metal machine that my hubby promised to dig out for me. I'll try it on there, one of the smaller patches so I don't cause a lot of damage. If I can't get it to work on that, then I'll give it back to him and explain that I jumped the gun.
Thank you all so much, you definately saved me a big headache and perhaps a broken Janome, which would have made me sad!!