is it your anatomy for the bent elbow - natural biomechanics? A friend of mine has a bent elbow through his swing till the area of release where he straightens it out. Nothing wrong with it. He has a sound approach, repeats shots, and balanced at the line. It may not be broke...... just a thought

First, make sure your grip measurements are accurate.  If you have to squeeze the ball to hang on to it, that may cause you bend your elbow so you don't drop it.  It all starts with the grip.

Sound advise here....  I also in the past have struggled with a bent elbow,  and did a combination of all things that have been mentioned here, and it took me a few yrs to correct it  (also fixed several things along the way).

But as mentioned above,  you have to experience different motions during practice to get a feel, which again as stated, wont happen overnite.  Good luck.

All very good points, indeed. I developed a bent elbow many years ago in an effort to
develop a power game (it didn't work for me).  It took me a very long time (and a healthy dose of patience) to correct it ( as Trash Heap said, it takes time!). Also, having a proper fit is a must, as GlobalDestruction pointed out

The best tip I ever got (and one that I pass on to my students who have the same problem) isto focus on your bowling shoulder throughout your stance and delivery.
Focus on keeping your bowling shoulder muscles RELAXED throughout the entire approach. By keeping your bowling shoulder muscles relaxed, it is impossible to bend
your elbow.

Good luck!