If I push the pedals down hard when cycling there is a creaking/groaning noise from where the shaft enters the motor unit. I checked that it wasn't that the pedals were well tight, but the noise persisits and is getting slowly worse - noticeably when going up hill. The chain wheel can be moved slightly on it's splines but I presume its not this? Is it the bearing in the motor /pedal output shaft? Is it repairable? Bike not used hugely - still on the original tyres! I don't know if origianl Panasonic motor can be repalced - or is there an alternate type that can be fitted/is compatible?