Something I have learnt. Fix all other shoulder, muscle issues and the pec minor stretches become easier.

Any glenohumeral instability flares them up further. That could mean anything from weak shifty shoulders including poor rotator cuff muscles.

Our problems are all around the muscle chain.

A good way to stretch the chest and front of shoulder is to put a rolled up towel between the blades and let your arm traction away towards the side.