Longines Ref 7186

New member here and not a watch expert. I inherited my father’s Longines in the mid 1990s. I sent the serial no. to Longines in Switzerland and they informed me it was a Ref. 7186 stainless steel purchased in 1961. I believe its movement is called a 280. On another forum some years ago I was told this was a fairly rare movement due to the reference no. I believe something to do with the railroad industry.

I’m in Seattle WA and interested in having it serviced. Any recommendations for a watchmaker and what a servicing might cost? Also if anyone knows more about the watch based on the ref no. and the attached photo I’d be grateful. Thanks in advance.