You can, of course, brush them, however this will not last long. More radical means of plastic washer embedded between the half-loops.
There is another way to get rid of the squeak. You need to shorten rod one half loop and put the loop inside a steel bearing ball.
Recommend to read
SECOND LIFE ANTI-AIRCRAFT “LIZARD”
The story began during the Second world war. The command of the Wehrmacht, faced at the first stage of hostilities with a large number of Soviet light armored vehicles - tanks BT, T-60,...
PEAR IS LIGHT
To fill the tank of a car in the field — for example, from a barrel or tank of the other vehicle drivers often use a simple hose and the so-called "sucking method", creating a vacuum...
