OneDragons wrote: Usually what I find is as you lift the elbow the weight shifts towards the head so less on the lower body. If you know what your doing the guy on the bottom can sometimes bridge up whilst straightening their arm and escape. If the bottom guy is not so good they will tap or get a lot of pain, normally I have found that to get a lot of pressure on the arm I have to transfer my weight on my hip closest to their head. Maybe I need to alter something, will see what others say and if I can improve.
It is difficult to articulate technical details in words but I will have a go. If you can't follow the test below, feel free to PM me and I'll send pictures.
As you raise your opponents elbow (doesn't need to be raised much using this method), simultaneously push their hand down towards their legs. Make sure that the back of their hand keeps contact with the mat and "brushes it". Also keep the whole lock tight and pulled in close to their body (i.e. don't allow their arm to straighten).
The above will keep the pressure on the elbow and enable you to keep your base neutral (i.e. avoid transfering weight up towards their head).
One other tip that will help prevent uke straightening their arm is to use a thumbless grip. To straighten their arm uke must break your grip. To do this they must act against the thumb. If you grip your opponents wrist using a thumbless grip and rotate your wrist forwards, when uke straightens their arm their energy acts against the hand (not the thumb). The only way to break the grip is to first move their arm inwards, which unfortunately for them tightens the lock.