I live in Mount Vernon and have used Master Marine for service on and off for 12 years...and still do. Previously for a Sea Sport with Yamahas, currently for a Tom Cat with Hondas.
The reason for the 'on and off' is because in my experience that is the nature of the service they provide. Sometimes very good, other times...not so much.
For example. Last year I had them do some DC electrical work on the the Tom Cat. Their rigging guys did just a great job, at a price I thought reasonable, and were consistently pleasant to deal with, even though quite busy.I believe the same workers are still there, and I would use them again for that kind of thing.
Other times, particularly with routine engine maintenance (a separate part of their business), you sometimes get the impression they all woke up on the wrong side of the bed that week, and would prefer you just go elsewhere...and so that is what you try to do. Bringing it up with the owners (who are frequently on site) does not help...they can be the grumpiest of all.
Have also used Tom and Jerry's, just on the east side of the Channel bridge once, but chose not to return. Have considered using the Honda outboard dealer in Bellingham, and have stopped by their place on occassion. They were competent, friendly and helpful. Except for the long road haul, I might be inclined to use them.
Finally, there is an independent outboard mechanic who used to work for Master Marine, quit and opened a shop on his own (Peterson's Marine). He is about a mile off the freeway on Stackpole, just south of MV, and he seems to have developed a following, at least for engine work. His overhead and hourly charge is lower than at MM.
Good luck.
KW
Tom Cat 25.5