On my S4 the right peg jams or used to.
Partly I think the heat of the exhaust dries out any lubricant, but also (on my S4) the casting for the right pillion peg hanger is too wide where the peg fits in. Because of that the ball bearing was coming too far out of it's hole & then jamming.
I took up some clearance by putting a shim under the metal plate & it has been fine ever since. Hope it works for you.
Jon