I ask him by bending slightly to the inside, Sliding my outside leg back, sitting back, pushing with my seat, giving with the reins, and squeezing with my legs. I always look up during transitions.
He seems a bit stiff/uncomfortable on that side, but he's perfect left lead. Any suggestions on building muscle on the one side? When he picks up the correct lead, should I keep him cantering for a while to stretch out the side and build muscle on the side?