Technical

So, having run my A4 very successfully on the rolling road and spent several months building a large radius track around my ‘man cave’ she was running well until the servo motor started to get sticky.  I gave it a carefull clean, lubed the mechanisms, turned it with my pinkie etc but it’s now almost given up and I think it may be shorting (a few sparks and a little smoke.) Is the motor repairable/replaceable? Is there recommended repairer If so. Thanks