<--------------There is Plenty of site sponsors, who may be able to assist.
Pedro at Coffee Parts is reknown for er coffee parts.
Other get some stick on rubber feet from your local hardware/kmart etc. It may be easier to replace all four, than just one.
I was thinking, a taller foot would be good as it would allow for a bit more jug clearance when steaming.....perhaps not Expobar height though!