Replacement springs tend to have open, unflattened

fractured wedge packer prior to silicon repair

Shallow wedged packer on original spring

underside of packer
ends, unlike the originals. These require matching new rubber wedged packers, similar to the ones sold by Ardinesh. Due to the increased height, the packing washers may be dispensed with.
If you are refitting the original springs but the original white wedged packers have disintegrated, do not throw the bits away. They are no longer available and have a unique shallow wedge angle. Just clean the bits, assemble the jigsaw and silicon them on to one of the packing washers. They then work fine.