(13/05/19)
Finally got round to looking at the damper hub that needs honing.
I purchased a 3 stone honer from our fav auction site. On arrival I realised it wouldn't work as the stones were the same size as the keyway, so would just get stuck.
I tried calling my usual machine shops I use thy all asked if the hub had a keyway. When told yes they all said they couldn't do it for the same reason.
Then it came to me, fill the keyway with something! Sourced some 1/4 x 1/4" brass bar. Then needed to get it to 1/8" deep. Got out the junior hacksaw and cut straight down the middle. What do you know, it fitted exactly.
Went to find the hone tool... spent the next two hours turning the garage upside down, still couldn't find it so had to order another one...now waiting for it to arrive!