Shimming modern GEM blades for use in vintage razors is nothing new and I have written about it ↪here. Here's another way of doing it and one I quite like - the rubber band shim: The rubber band in the following pictures is 1 inch long (when laid flat) and ¼ inch wide (rubber bands seem to be measured in inches). The blade with the rubber band is 2.19mm thick, which is slightly more than required, but it works really well. The rubber has the added advantage that it properly removes any blade chatter. One thing to keep in mind when using the rubber band shim is that the rubber band stops the blade from sliding around in the head, so you shouldn't rely on the spring in the head moving the blade towards the blade stops. Just make sure the blade is seated properly when closing the head. One disadvantage of the rubber band shim is the availability of suitable rubber bands. I have one rubber band of the correct size and no idea where it came from. If you know of a good source of 1 (maybe 1¼) inch long, ¼ inch wide rubber bands, please let me know.