Thank you, bkay for that link. I had never seen the Bernina's “height compensation tool” I have several of the pointy ones and another one that is rectangle with the ends of which have different heights. I think I learned about going over thick seams, maybe from an early Sewing With Nancy show. I have used cardboard or a seam/hem from cut-off jeans or just heavy fabric rolled up. The Bernina one reminds me of a feeler gauge. I went searching for one online as she indicated that they were $1 from a Bernina dealer (but that was back in 2014). I found a few online that were over $8.
Janey - Neat people never make the exciting discoveries I do.