Further developments Phil. D211 is now running silky smooth i can only think that the wire sand pipes touching the wheels were the problem. The sound came back on and lasted for about 2 circuits then broke up and stopped, this also affected the running? I was going to bite the bullet, take the top off and investigate the speaker as you suggested but before i did i just gave the body a little squeeze and the sound returned, release the squeeze and it goes again. Would this be the contacts being suspect as you suggested do you think?