I had tried MeArm and found that when the arm move forward, the weight cause the base servo flick.
I think it will be better to make some spring like mechanism to absorb the movement and hence propose two modification.
1. Cut straw (u can also install small sphere such as BB bullets instead) into small pieces and stick it with hot glue (notice the direction), the plastic straw provide cushion effect and support the base movement.
2. It is not necessary, but if u glue a piece of plastic sheet may cause the movement less "friction"