Speedo oil seal

Hi guys.

Has anyone ever tried changing the speedo seal please?

When fitting there doesnt seem to be any space where it locks itself in… as soon as I move its housing, it falls off…

I tried the other day on a LT 230 I am fitting with new seals and gaskets to remove the drive. Just can not get the speedo drive out so as there is no sign it was leaking decided to leave alone.
Recon one of the O rings in the gasket set is what seals it and the whole thing is kept in place by the little plate that keeps the cable drive in place.

Yep sealed with O ring on the shaft/tube that holds the speedo drive.

Thanks guys! Would you mind sending a picture of it please? As the only one I found very similar to what was already there before is the one I posted up here. However, for the new one, its outer lip seems much bigger, whilst overall shape is the same as the old ... the previous seal was rock solid and broke off.