Hello, It seems one of my 6646 transformers has decided it doesn't want to work anymore. The layout, an ongoing work in progress, is 110 volt residential circuit. I was using 2 6646's. one for the catenary and the other for the track. I run both my old analog locos and some newer digital in conventional mode. I have a 6627 transformer, blue plastic, and was looking through the literature with the digital locos. I see a picture of a transformer, crossed out with number 6600, 6699. can i use the 6627 or do i need to track down a 6646? what other transformers are there that are compatible? I don't want to smoke anything because i run the wrong transformer. the white 6646 failing totally caught me by surprise. thanks in advance for any help.