Yes it's normal. These heads work off friction to keep the blades down, not a rubber band or O-ring. I don't remember the ones I had being really tight, but they were snug enough to hold the blades down well. For this reason though I don't put them in the same class as some other mechanicals. I feel it takes more energy to use them than the standard mechanical. However if you have the energy (which you do) to use them they work very well.

Paul