You are hyper extending your elbows when at full extension.
Part of my problems too....
I have that tendency in my knees and shoulders too.
Use your large muscle groups.
When you lock your elbow like that, the strain is on your joints and tendons.
Step back and use some progressions - I like the ones in Convict Conditioning: How to Bust Free of All Weakness--Using the Lost Secrets of Supreme Survival Strength: Paul Wade: 9780938045762: Amazon.com: Books, but the ones in the Primal Blueprint Fitness (sticky link in this forum) are also very good.
I second the hyperextension appearance - I'm nowhere near as qualified as Coach Palfrey, but I'd try taking a little of that extra stress off the joint.