Re: Rubber insulators
Stretch it. I promise you, it will go. It takes some work and effort but all nine bolts will go in. Make sure the ends of the metal plates do not overlap and lay flush against each other.
Just in case you have a set of instructions that have the wrong information; you'll want a sandwich. from the outside in > Sprocket, rubber, spokes, rubber, metal plates. Do not bolt the sprocket directly to the spokes. There have been some kits with instructions that tell you to do that. IT IS WRONG.
Also we can't stress enough the importance of getting the sprocket perfectly centered on the rear hub. It must spin true with no wobbles.
Good luck. Let us know how it goes.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"