Hi, I started playing bass half a year ago and have trouble with my fretting hand. Recently I've been playing Billie Jean bassline a lot, and have trouble keeping the tempo. I play it at regualr tempo and my fretting hand wrist bends when I play it. I start to press really hard against the neck with my thumb, my playing gets sloppy and my fingers get slower and slower. This makes it hard for me to play the bassline longer than a minute at a regular tempo. I realise that my wrist should stay straight throughout the playing but I just can't play at a regular tempo when my wrist is straight because the neck of the bass just falls into my palm and half of my thumb crosses the top of the neck and it can't stay around the middle of the neck. This is a problem because when I practice staying in sync and keeping the tempo with a drummer I cramp up and just can't continue. I would very much appreciate some advice regarding this problem. Also I am new to this forum and if anything like this was already answered(I didn't notice) I would be grateful if you let me know so I can remove this thread.