Rail Lock, I'm not sure if this is the right term.
It's located on the right hand side, in front.
It pivots, clockwise and pushes against the rail to lock the lens, once your focused. Needs something done with it. It's not locking real well.
What can be done?
Thanks for any suggestions.

http://www.southbristolviews.com/pics/Graphic/manual-pdf/AnniversaryService1.pdf
pdf page 6 - focusing pinion tension, aka focus lock.

The screw/stud that the lever is on has 3 start points. Sometimes starting the lever at another point will allow it to increase the tension on the pinion to an acceptable operating level without the lever hitting the rails. The rails must be removed to remove the lever and the lever can be difficult to reinstall.

I do not know what the pads are made of but a good substitute should not be too hard to find.

Ok... got it repaired... thank you.

Before disassembling, when I used the focus lock, it would shift the rail towards the other side, thus I thought it was applying a horizontal pressure, to lock the rails.

I was very surprised, when I took it apart, that the pressure was suppose to be applied vertically, as in a pressure squeeze, when the focus lock was used.

Marking the square metal piece, that actually applies the pressure, before taking off the lever, I further discovered that use over the years past, had built up next to the stud some deposits, that had compacted over the years, thus causing it to shift towards the other rail horizontally, and not allowing a full vertical squeeze. So it wouldn't really lock.

Another interesting note, there is no 'pad'. The square can be put in four positions, allowing adjustment as the 'square squeeze plate' wears. In fact someone in the distant past did just that, as one edge shows a lot of wear. Must have constantly adjusted focus with the lock in place.