To answer my own question, my Plus 8 has 27mm O/D bushes. Fortunately I put a pair into stock about 10 years ago, Peter Mulberry was making some (cutting down a longer bush) and I thought it a good idea to put a pair into stock.
First job was to mark the inner rod ends so I know which side faces front and mark it with tape. Then undo the locking nut securing the end to the rod, remember the thread is counter clockwise, keep the lock nut abutting the rod end. Remove the bolt securing the rod end to the rack, and unscrew the rod end from the control rod, make sure the locking nut stays in place.
![[Linked Image]](https://www.tm-img.com/images/2020/02/28/The-rack.jpg)
Once removed the bush can be pressed out with the aid of a couple of old sockets, a large one to go under the rod and a small one (approx 26mm diameter) to push the bush through
The old bush looks a bit tired
![[Linked Image]](https://www.tm-img.com/images/2020/02/28/The-old-bush.jpg)
Old bush on left, new pair on right, although they have been lingering in the garage for about 10 years waiting for the call
![[Linked Image]](https://www.tm-img.com/images/2020/02/28/The-end-and-bush.jpg)
Press the new bush in and then screw the end back onto the control rod and fit to rack.
The mystery remains, when did the 28.5mm bush come into use ?