[Accelo]

Here is a picture of the speedometer parts.
I have rebuild 100.s of these and never had to replace a bullet.
Replace the "O'" ring and a seal and your good to go.
The number one cause of oil leaks in this setup is warn shafts on the plastic gears. The steel shell never wears enough to replace. I believe you are on the right track to stop this adapter from leaking.