I've heard other issues with the sheets, which could have just been the batch. I still have the first original batch I ordered, so I don't know if another one would give me problems.
I don't have any secret trick, it's all been hit or miss when I first started using these. I just spray the cocoa butter the same for anything else I do.
I have used them without the cocoa butter and they worked, but I felt the image wasn't as bright as with the white. This shows without, but the logo is white, and this is way is too yellow from the white chocolate.
But, this photo is of my cat, and the white chocolate works better than white cocoa butter because it's her blond color:
Since Tomric only sells these and are not the maker, I don't know if any info from Deco in the UK or Chocolate World in Belgium would be better. They are the ones that developed it. I was going to order the sheets from them until I found that Tomric sold them.
I've never had any trouble with the printer clogging. www.tastyfotoart.com is the other place I ordered ink from. I liked them better because the came with the chips that the Canon printers have, and I didn't have to move chips between cartridges.
I can still have problems occasionally, but it's mostly been from the cocoa butter not being the right temp or something.