IMHO....spend the twenty even though it's a rip.

You didn't say how old or what model but generally.....those aftermarket "vibration absorbers" have a different purpose from the machine's original feet. The machine's feet are designed to provide a solid base so that the machine's suspension components can handle vibration and imbalance when they occur. For that, they need equal or almost-equal bearing on those supporting feet in order to work properly. I would not introduce a material of unknown/dissimilar compressibility on a single foot for that reason.

Get the new foot. It's only $20 (balanced against your initial investment in those machines ... pocket change).

All of the anti-vib pads I have seen cost more than $20.

Get the correct Miele OEM foot. It's a drop in the bucket compared to what you have invested in the machine.