I have an older Dolphin which is great but the motor is almost "frozen" and only operates periodically until the motor is manually moved slightly and then it works again for a short time. I see that you do not have a replacement in stock. My current motor is a 6H Advantage from March 1, 2005 and has aquited itself for lasting so long. The only replacement that I can find is on line but it is a model 6HR. Is it a compatable replacement. The unit I have is powered from the electronics contained within the wheeled carrier not from a separate power pack.