I've got the exact same problem. Had my diff oil changed, bearings changed, been up on the ramp getting checked over and still none the wiser. Apart from now I've picked up a thudding noise when im driving lol
If any spaces come available could i please be pm'd? Don't know how but i missed that we had a stand for this and would love to be part of it if possible.
If there do happen to be any other spaces come up i may also be interested as i think im free from work that weekend now , be my first show in the zed.