Hey bud,
If you still want the sponge, send me your address. We'll work the postage out after, no probs to me. I think its only going to be about £1.05 anyways so i'm easy.
I'd completely forgotten about the rubber cover at the back, thank you. That'll be really useful as i'm racing my Mid again after 24 years.
We have some Grundfos water pumps at my workplace that require massive clamps that have a rubber sleeve inside them. Its not far off the same shape and could work.
I'll do some digging tomorrow.