For owner change and re-change, make sure in advance that both he and you receive WGT mails without problems, that is, the account mails - e.g. about the heart ball gift. Each way, the prospective new owner must receive a WGT mail with a link to click on.
Otherwise, one of the changes may fail (see me as a victim ;) )
OTOH, Skype might do the job for you. Connect, let him view your screen ("+" sign), He will then see your screen and mouse and will be able to guide you through the work.
IMHO, the more secure way.