I have the above folding bike and the motor has started to get noisy, does anyone know whether worn parts inside the motor can be renewed or is it a sealed unit and the motor has to be replaced. It still runs ok but it getting noisier when used constantly for a while, short trips such as to the shops are fine, but we did part of the Tissington Trail at the weekend and as it was uphill I was using the motor most of the time, this was when we noticed the noise, I am heavy but within the weight limits of the bike by a long way, could the motor just have gotten hot?. Hubby is able to do some repairs but has never worked on the motor, if anyone knows anymore please let me know, the company will do repairs but not servicing.